Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On Fri, Jun 05, 2015 at 08:22:31 +0800, Qiao,Liyong wrote: On 2015年06月04日 20:09, Jiri Denemark wrote: On Tue, Jun 02, 2015 at 11:02:27 -0600, Eric Blake wrote: On 06/02/2015 07:56 AM, Qiao, Liyong wrote: Hi Eric Thanks for replying the mail, replied in lines. +virdomainMigrateGetParameters(virDomainPtr domain, + int *level, + int *threads, + int *dthreads, + int flags) + I'd rather we used virTypedParameters, to make it easier to use the same API to pass ALL future possible tuning parameters, rather than just hard-coding to only the parameters of this one feature. Okay ,that sound good, but if virTypedParameters can be passed to qemu_driver such as qemu_monitor_json.c qemu_monitor_text.c ? [Your quoting style makes it very hard to distinguish original text from added text. Please consider changing your outgoing mail process to ensure that you add another level of quoting to all previous text so that your added text is the only unquoted text. Also, configure your mailer to wrap long lines.] Use existing API for a guide - for example, virDomainSetBlockIoTune takes virTypedParamters, as well as defines a specific set of parameters that it will understand. And do we actually need to changed these migration parameters on the fly when migration is already running. I can imagine we would need to do so for some parameters but multithreaded compression sounds like something that needs to be configured when migration starts and there's nothing to be tuned on the fly. If this is the case, I think we should just add these new parameters to virDomainMigrate3 instead of requiring another API to be called to actually configure multithreaded compression. The separate API makes it a bit harder to repeat migration (which previously failed) with a different parameters (e.g., without multithreaded compression). hi jirka thanks for your advice, that make sense for me. if I understanding you correctly, then we need only do this virsh migrate --live --compressed --compress-level 1--compress-threads 8 --decompress-threads 2 and all compressed parameters (compress-level ,compress-threads, decompress-threads) only be specified when we do call virDomainMigrate3 instead of expose to user by 'virsh migrate-setparameters' ? Right, although there still seems to be an open question whether we can reuse --compressed or we need to come up with another option so that we can independently turn on XBZRLE and multithreaded compression. Jirka -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
-Original Message- From: Qiao, Liyong Sent: Wednesday, June 3, 2015 7:49 AM To: Eric Blake; Feng, Shaohe; libvir-list@redhat.com Cc: Bhandaru, Malini K; Ding, Jian-feng; Chylinski, Arek; Koniszewski, Pawel; Li, Liang Z; berra...@redhat.com; veill...@redhat.com Subject: Re: [RFC] libvirt support multi-thread compression for live migration On 2015年06月03日 01:02, Eric Blake wrote: On 06/02/2015 07:56 AM, Qiao, Liyong wrote: Hi Eric Thanks for replying the mail, replied in lines. +virdomainMigrateGetParameters(virDomainPtr domain, + int *level, + int *threads, + int *dthreads, + int flags) + I'd rather we used virTypedParameters, to make it easier to use the same API to pass ALL future possible tuning parameters, rather than just hard-coding to only the parameters of this one feature. Okay ,that sound good, but if virTypedParameters can be passed to qemu_driver such as qemu_monitor_json.c qemu_monitor_text.c ? [Your quoting style makes it very hard to distinguish original text from added text. Please consider changing your outgoing mail process to ensure that you add another level of quoting to all previous text so that your added text is the only unquoted text. Also, configure your mailer to wrap long lines.] hi Eric, sorry about the inconvenient mail client, I switch outlook to thunder bird, hopes it will be better. Use existing API for a guide - for example, virDomainSetBlockIoTune takes virTypedParamters, as well as defines a specific set of parameters that it will understand. The set of parameters can be enlarged without needing a new API (good for backporting features without requiring a .so version bump), but for any given libvirt version, the set of features understood is finite and limited to what you can translate to the QMP call. So qemu_driver.c would take the virTypedParameters, reject the ones it does not understand, and convert the ones it does understand into the 'int level, int threads, int dthreads' parameters used in qemu_monitor_json.c where you drive the actual QMP command with fixed parameters and types. ah, that helps, thanks for kindly supporting, we will think a bit more to how implement this API (taken virTypedParamters as parameter) If we think that it is worth always turning on both compression styles simultaneously, then reuse the bit. Otherwise, we need a different bit, and users can choose which (or both) of the two compression styles as desired. +1 for reuse compressed, and we can set compress-level, Consider this scenario : one of the host/hypervisor are high cpu/memory usage, Cloud Tool, such as Openstack can make a strategy that do not compression by multi-thread, for high cpu usage, they just want to use xbzrle. Is this scenario reasonable? +compress-threads, compress-dthreads by +virdomainMigrateSetParameters(maybe some new virsh command--- +migrate-setparameter) But how can we passing these parameter when we using `virsh migrate `, is there any parameter we can use in 'virsh migrate' command ? Can you point me out ? The underlying API already has a form that takes virTypedParameters (see virDomainMigrate3()), so your first task is to figure out how to extend the API to expose new typed parameters for your new migration tunings. Once that is done, then you can worry about how to tweak the 'virsh migrate' client to pass in those new parameters. -- BR, Eli(Li Yong)Qiao -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On 2015年06月04日 20:09, Jiri Denemark wrote: On Tue, Jun 02, 2015 at 11:02:27 -0600, Eric Blake wrote: On 06/02/2015 07:56 AM, Qiao, Liyong wrote: Hi Eric Thanks for replying the mail, replied in lines. +virdomainMigrateGetParameters(virDomainPtr domain, + int *level, + int *threads, + int *dthreads, + int flags) + I'd rather we used virTypedParameters, to make it easier to use the same API to pass ALL future possible tuning parameters, rather than just hard-coding to only the parameters of this one feature. Okay ,that sound good, but if virTypedParameters can be passed to qemu_driver such as qemu_monitor_json.c qemu_monitor_text.c ? [Your quoting style makes it very hard to distinguish original text from added text. Please consider changing your outgoing mail process to ensure that you add another level of quoting to all previous text so that your added text is the only unquoted text. Also, configure your mailer to wrap long lines.] Use existing API for a guide - for example, virDomainSetBlockIoTune takes virTypedParamters, as well as defines a specific set of parameters that it will understand. And do we actually need to changed these migration parameters on the fly when migration is already running. I can imagine we would need to do so for some parameters but multithreaded compression sounds like something that needs to be configured when migration starts and there's nothing to be tuned on the fly. If this is the case, I think we should just add these new parameters to virDomainMigrate3 instead of requiring another API to be called to actually configure multithreaded compression. The separate API makes it a bit harder to repeat migration (which previously failed) with a different parameters (e.g., without multithreaded compression). hi jirka thanks for your advice, that make sense for me. if I understanding you correctly, then we need only do this virsh migrate --live --compressed --compress-level 1--compress-threads 8 --decompress-threads 2 and all compressed parameters (compress-level ,compress-threads, decompress-threads) only be specified when we do call virDomainMigrate3 instead of expose to user by 'virsh migrate-setparameters' ? I think that's good for me, and make user easy to start LM. thanks, Eli. Jirka -- BR, Eli(Li Yong)Qiao attachment: liyong_qiao.vcf-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On 2015年06月04日 20:01, Jiri Denemark wrote: On Wed, Jun 03, 2015 at 15:13:17 +, Feng, Shaohe wrote: Eric, Thank you for reply. Is it necessary to expose these two APIs to user application? + virdomainMigrateSetCapabilities + virdomainMigrateGetCapabilities For qemu , the migration capabilities are xbzrle, rdma-pin-all, auto-converge, zero-blocks and compress. No, these capabilities are either turned on/off based on flags passed to virDomainMigrate3 API. I think we need to call qemuMonitorGetMigrationCapability when qemuMigrationSetCompression if the source/dest node doesn't support 'compress' capability, we need to stop migration if flags contain VIR_MIGRATE_COMPRESSED (currently it stands for xbzrle, and Eric's previous mail suggest we share this flag with 'compress') -Eli. Jirka -- BR, Eli(Li Yong)Qiao attachment: liyong_qiao.vcf-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On 06/04/2015 06:31 PM, Qiao,Liyong wrote: On 2015年06月04日 20:01, Jiri Denemark wrote: On Wed, Jun 03, 2015 at 15:13:17 +, Feng, Shaohe wrote: Eric, Thank you for reply. Is it necessary to expose these two APIs to user application? + virdomainMigrateSetCapabilities + virdomainMigrateGetCapabilities For qemu , the migration capabilities are xbzrle, rdma-pin-all, auto-converge, zero-blocks and compress. No, these capabilities are either turned on/off based on flags passed to virDomainMigrate3 API. I think we need to call qemuMonitorGetMigrationCapability when [It's hard to read replies that aren't visually distinct from the rest of the text; you'll notice that most posters on this list leave a blank line before and after any text they add, so that a scan of the left-most column can easily spot blanks as a key for where new content begins] qemuMigrationSetCompression if the source/dest node doesn't support 'compress' capability, we need to stop migration if flags contain VIR_MIGRATE_COMPRESSED (currently it stands for xbzrle, and Eric's previous mail suggest we share this flag with 'compress') No, I was asking whether libvirt's 'compress' flag should imply all possible compression at once, or whether there are cases where xbzrle and multi-thread are independently useful and should not both be on at once. If it is safe to always use both, then we don't need a new flag, but I don't know if it is safe. The migration handshake is already set up to negotiate capabilities between source and destination, whether it takes one flag (turning on both compressions, or gracefully falling back to xbzrle alone) or two (one per compression type, and erroring out if a request is made for an unsupported compression). -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On 2015年06月04日 20:01, Jiri Denemark wrote: On Wed, Jun 03, 2015 at 15:13:17 +, Feng, Shaohe wrote: Eric, Thank you for reply. Is it necessary to expose these two APIs to user application? + virdomainMigrateSetCapabilities + virdomainMigrateGetCapabilities For qemu , the migration capabilities are xbzrle, rdma-pin-all, auto-converge, zero-blocks and compress. No, these capabilities are either turned on/off based on flags passed to virDomainMigrate3 API. I think we need to call qemuMonitorGetMigrationCapability when [It's hard to read replies that aren't visually distinct from the rest of the text; you'll notice that most posters on this list leave a blank line before and after any text they add, so that a scan of the left-most column can easily spot blanks as a key for where new content begins] qemuMigrationSetCompression if the source/dest node doesn't support 'compress' capability, we need to stop migration if flags contain VIR_MIGRATE_COMPRESSED (currently it stands for xbzrle, and Eric's previous mail suggest we share this flag with 'compress') No, I was asking whether libvirt's 'compress' flag should imply all possible compression at once, or whether there are cases where xbzrle and multi- thread are independently useful and should not both be on at once. If it is safe to always use both, then we don't need a new flag, but I don't know if it is safe. Multiple thread compression is CPU-intensive, while xbzrle is RAM-intensive. Although they can co-work correctly, there is no evidence show that turning both on will achieve better performance than using xbzrle or multi-thread independently. May be it's better to let the users decide which one to use depend on their specific use case. The migration handshake is already set up to negotiate capabilities between source and destination, whether it takes one flag (turning on both compressions, or gracefully falling back to xbzrle alone) or two (one per compression type, and erroring out if a request is made for an unsupported compression). -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On Wed, Jun 03, 2015 at 15:13:17 +, Feng, Shaohe wrote: Eric, Thank you for reply. Is it necessary to expose these two APIs to user application? + virdomainMigrateSetCapabilities + virdomainMigrateGetCapabilities For qemu , the migration capabilities are xbzrle, rdma-pin-all, auto-converge, zero-blocks and compress. No, these capabilities are either turned on/off based on flags passed to virDomainMigrate3 API. Jirka -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On Tue, Jun 02, 2015 at 11:02:27 -0600, Eric Blake wrote: On 06/02/2015 07:56 AM, Qiao, Liyong wrote: Hi Eric Thanks for replying the mail, replied in lines. +virdomainMigrateGetParameters(virDomainPtr domain, + int *level, + int *threads, + int *dthreads, + int flags) + I'd rather we used virTypedParameters, to make it easier to use the same API to pass ALL future possible tuning parameters, rather than just hard-coding to only the parameters of this one feature. Okay ,that sound good, but if virTypedParameters can be passed to qemu_driver such as qemu_monitor_json.c qemu_monitor_text.c ? [Your quoting style makes it very hard to distinguish original text from added text. Please consider changing your outgoing mail process to ensure that you add another level of quoting to all previous text so that your added text is the only unquoted text. Also, configure your mailer to wrap long lines.] Use existing API for a guide - for example, virDomainSetBlockIoTune takes virTypedParamters, as well as defines a specific set of parameters that it will understand. And do we actually need to changed these migration parameters on the fly when migration is already running. I can imagine we would need to do so for some parameters but multithreaded compression sounds like something that needs to be configured when migration starts and there's nothing to be tuned on the fly. If this is the case, I think we should just add these new parameters to virDomainMigrate3 instead of requiring another API to be called to actually configure multithreaded compression. The separate API makes it a bit harder to repeat migration (which previously failed) with a different parameters (e.g., without multithreaded compression). Jirka -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
Eric, Thank you for reply. Is it necessary to expose these two APIs to user application? + virdomainMigrateSetCapabilities + virdomainMigrateGetCapabilities For qemu , the migration capabilities are xbzrle, rdma-pin-all, auto-converge, zero-blocks and compress. Sorry , I use outlook. Will change to thunderbird. -Original Message- From: Qiao, Liyong Sent: Wednesday, June 3, 2015 7:49 AM To: Eric Blake; Feng, Shaohe; libvir-list@redhat.com Cc: Bhandaru, Malini K; Ding, Jian-feng; Chylinski, Arek; Koniszewski, Pawel; Li, Liang Z; berra...@redhat.com; veill...@redhat.com Subject: Re: [RFC] libvirt support multi-thread compression for live migration On 2015年06月03日 01:02, Eric Blake wrote: On 06/02/2015 07:56 AM, Qiao, Liyong wrote: Hi Eric Thanks for replying the mail, replied in lines. +virdomainMigrateGetParameters(virDomainPtr domain, + int *level, + int *threads, + int *dthreads, + int flags) + I'd rather we used virTypedParameters, to make it easier to use the same API to pass ALL future possible tuning parameters, rather than just hard-coding to only the parameters of this one feature. Okay ,that sound good, but if virTypedParameters can be passed to qemu_driver such as qemu_monitor_json.c qemu_monitor_text.c ? [Your quoting style makes it very hard to distinguish original text from added text. Please consider changing your outgoing mail process to ensure that you add another level of quoting to all previous text so that your added text is the only unquoted text. Also, configure your mailer to wrap long lines.] hi Eric, sorry about the inconvenient mail client, I switch outlook to thunder bird, hopes it will be better. Use existing API for a guide - for example, virDomainSetBlockIoTune takes virTypedParamters, as well as defines a specific set of parameters that it will understand. The set of parameters can be enlarged without needing a new API (good for backporting features without requiring a .so version bump), but for any given libvirt version, the set of features understood is finite and limited to what you can translate to the QMP call. So qemu_driver.c would take the virTypedParameters, reject the ones it does not understand, and convert the ones it does understand into the 'int level, int threads, int dthreads' parameters used in qemu_monitor_json.c where you drive the actual QMP command with fixed parameters and types. ah, that helps, thanks for kindly supporting, we will think a bit more to how implement this API (taken virTypedParamters as parameter) If we think that it is worth always turning on both compression styles simultaneously, then reuse the bit. Otherwise, we need a different bit, and users can choose which (or both) of the two compression styles as desired. +1 for reuse compressed, and we can set compress-level, +compress-threads, compress-dthreads by +virdomainMigrateSetParameters(maybe some new virsh command--- +migrate-setparameter) But how can we passing these parameter when we using `virsh migrate `, is there any parameter we can use in 'virsh migrate' command ? Can you point me out ? The underlying API already has a form that takes virTypedParameters (see virDomainMigrate3()), so your first task is to figure out how to extend the API to expose new typed parameters for your new migration tunings. Once that is done, then you can worry about how to tweak the 'virsh migrate' client to pass in those new parameters. -- BR, Eli(Li Yong)Qiao -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On 2015年06月03日 01:02, Eric Blake wrote: On 06/02/2015 07:56 AM, Qiao, Liyong wrote: Hi Eric Thanks for replying the mail, replied in lines. +virdomainMigrateGetParameters(virDomainPtr domain, + int *level, + int *threads, + int *dthreads, + int flags) + I'd rather we used virTypedParameters, to make it easier to use the same API to pass ALL future possible tuning parameters, rather than just hard-coding to only the parameters of this one feature. Okay ,that sound good, but if virTypedParameters can be passed to qemu_driver such as qemu_monitor_json.c qemu_monitor_text.c ? [Your quoting style makes it very hard to distinguish original text from added text. Please consider changing your outgoing mail process to ensure that you add another level of quoting to all previous text so that your added text is the only unquoted text. Also, configure your mailer to wrap long lines.] hi Eric, sorry about the inconvenient mail client, I switch outlook to thunder bird, hopes it will be better. Use existing API for a guide - for example, virDomainSetBlockIoTune takes virTypedParamters, as well as defines a specific set of parameters that it will understand. The set of parameters can be enlarged without needing a new API (good for backporting features without requiring a .so version bump), but for any given libvirt version, the set of features understood is finite and limited to what you can translate to the QMP call. So qemu_driver.c would take the virTypedParameters, reject the ones it does not understand, and convert the ones it does understand into the 'int level, int threads, int dthreads' parameters used in qemu_monitor_json.c where you drive the actual QMP command with fixed parameters and types. ah, that helps, thanks for kindly supporting, we will think a bit more to how implement this API (taken virTypedParamters as parameter) If we think that it is worth always turning on both compression styles simultaneously, then reuse the bit. Otherwise, we need a different bit, and users can choose which (or both) of the two compression styles as desired. +1 for reuse compressed, and we can set compress-level, compress-threads, compress-dthreads by virdomainMigrateSetParameters(maybe some new virsh command--- migrate-setparameter) But how can we passing these parameter when we using `virsh migrate `, is there any parameter we can use in 'virsh migrate' command ? Can you point me out ? The underlying API already has a form that takes virTypedParameters (see virDomainMigrate3()), so your first task is to figure out how to extend the API to expose new typed parameters for your new migration tunings. Once that is done, then you can worry about how to tweak the 'virsh migrate' client to pass in those new parameters. -- BR, Eli(Li Yong)Qiao attachment: liyong_qiao.vcf-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
[correcting list address: libvirt-list, not libver-list]
On 06/02/2015 05:58 AM, Feng, Shaohe wrote:
Hi folks:
I'd like to request some comments on enabling multi-thread compression in
libvirt.
Currently, qemu upstream has supported multi-thread compression for live
migration.
$ git log 263170e~1..362ba4e -oneline
This can preserve bandwidth and speed up the live migration process, so this
is an import
feature we need to enable so for other high level such as openstack will be
benefit.
We plan to add feature of multi-thread compression and actually the patch is
working in process.
Now some things need for comments.
1. Expose new set/get multi-thread compression parameters API for live
migration.
Now qemu only supports zlib compression. Maybe LZ4 and gzip will be
supported later.
but there are 3 parameters needed by qemu currently.
compress-level: compression level, default is 1. For zlib compression, it
is from 0-9, 0 means use default level, 9 means high compressed.
compress-threads: compression thread count for multi-thread migration,
default is 8 in qemu.
decompress-threads: decompression thread count for multi-thread migration,
default is 2 in qemu
So in libvirt we will expose the public symbols as follow, we only 3
parameters,
missing compression method(zlib, LZ4 and gzip) parameters, for qemu do not
support it at present.
index d851225..103b3b9 100644
--- a/include/libvirt/libvirt-domain.h
+++ b/include/libvirt/libvirt-domain.h
@@ -798,6 +798,17 @@ int virDomainMigrateGetMaxSpeed(virDomainPtr domain,
unsigned long *bandwidth,
unsigned int flags);
+int virdomainMigrateSetParameters(virDomainPtr domain,
+ int level,
+ int threads,
+ int dthreads,
+ int flags)
+int virdomainMigrateGetParameters(virDomainPtr domain,
+ int *level,
+ int *threads,
+ int *dthreads,
+ int flags)
+
I'd rather we used virTypedParameters, to make it easier to use the same
API to pass ALL future possible tuning parameters, rather than just
hard-coding to only the parameters of this one feature.
For virdomainMigrateSetParameters, if specifying a negative value to level,
threads, and dthreads parameters, such as -1,
means do not set the parameters.
The underlying code will not pass the corresponding parameters to qemu
monitor.
Such as threads and dthreads is -1, then pass the following json streaming to
qemu.
{ execute: migrate-set-parameters , arguments: { compress-level: 1 }
}
The virsh will expose the two commands:
# virsh migrate-setparameters domain [--level level] [--threads threads]
[--dthreads dthread]
# virsh migrate-getparameters domain
2. How to enable multi-thread compression in application interface?
There is not a special interface for setting migration capabilities.
But we can set the capabilities when execute an virsh command as
following:
$ migrate --live] [--offline] [--p2p] [--direct] [--tunnelled]
[--persistent] [--undefinesource] [--suspend] [--copy-storage-all]
[--copy-storage-inc] [--change-protection] [--unsafe] [--verbose]
[--compressed] [--abort-on-error] domain desturi [migrateuri]
[graphicsuri] [listen-address] [dname] [--timeout number] [--xml
string]
There is already a compressed option, here compressed means xbzrle not
multi- compressed.
can I rename the compressed to xbzrle?
If we think that it is worth always turning on both compression styles
simultaneously, then reuse the bit. Otherwise, we need a different bit,
and users can choose which (or both) of the two compression styles as
desired.
so we add another option for multi-thread compression, which is better option
name? -multi- compressed ?
Any way this is confuse to user. We need to
distinguishhttp://dict.youdao.com/w/distinguish/ these two.
So I wonder should we expose new API to enable the migrate multi-thread
compress.
+int virdomainMigrateEnableMultiThreadCompress (virDomainPtr domain, int
flags)
It will pass the following command to qemu monitor.
{ execute: migrate-set-capabilities , arguments: { capabilities: [
{ capability: compress, state: true } ] } }
NOTE: Now, multiple thread compression can co-work with xbzrle. When xbzrle
is on, multiple thread compression will only work at the first round of RAM
data sync.
Qemu, $ git show 98f1138902195bd9ab8a753d0ee2cf2a0a88b6e8
if compress and xbzrle are both on, compress only takes effect in the ram
bulk stage, after that, it will be disabled and only xbzrle takes effect,
this can help to minimize migration traffic.
3. Migration between different livirt/qemu
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
Hi Eric
Thanks for replying the mail, replied in lines.
BR, Eli(Li Yong)Qiao
-Original Message-
From: Eric Blake [mailto:ebl...@redhat.com]
Sent: Tuesday, June 02, 2015 8:21 PM
To: Feng, Shaohe; libvir-list@redhat.com
Cc: Qiao, Liyong; Bhandaru, Malini K; Ding, Jian-feng; Chylinski, Arek;
Koniszewski, Pawel; Li, Liang Z; berra...@redhat.com; veill...@redhat.com
Subject: Re: [RFC] libvirt support multi-thread compression for live migration
[correcting list address: libvirt-list, not libver-list]
On 06/02/2015 05:58 AM, Feng, Shaohe wrote:
Hi folks:
I'd like to request some comments on enabling multi-thread compression in
libvirt.
Currently, qemu upstream has supported multi-thread compression for live
migration.
$ git log 263170e~1..362ba4e -oneline
This can preserve bandwidth and speed up the live migration process,
so this is an import feature we need to enable so for other high level such
as openstack will be benefit.
We plan to add feature of multi-thread compression and actually the patch is
working in process.
Now some things need for comments.
1. Expose new set/get multi-thread compression parameters API for live
migration.
Now qemu only supports zlib compression. Maybe LZ4 and gzip will be
supported later.
but there are 3 parameters needed by qemu currently.
compress-level: compression level, default is 1. For zlib compression, it
is from 0-9, 0 means use default level, 9 means high compressed.
compress-threads: compression thread count for multi-thread migration,
default is 8 in qemu.
decompress-threads: decompression thread count for multi-thread
migration, default is 2 in qemu
So in libvirt we will expose the public symbols as follow, we only 3
parameters, missing compression method(zlib, LZ4 and gzip) parameters, for
qemu do not support it at present.
index d851225..103b3b9 100644
--- a/include/libvirt/libvirt-domain.h
+++ b/include/libvirt/libvirt-domain.h
@@ -798,6 +798,17 @@ int virDomainMigrateGetMaxSpeed(virDomainPtr domain,
unsigned long *bandwidth,
unsigned int flags);
+int virdomainMigrateSetParameters(virDomainPtr domain,
+ int level,
+ int threads,
+ int dthreads,
+ int flags) int
+virdomainMigrateGetParameters(virDomainPtr domain,
+ int *level,
+ int *threads,
+ int *dthreads,
+ int flags)
+
I'd rather we used virTypedParameters, to make it easier to use the same API to
pass ALL future possible tuning parameters, rather than just hard-coding to
only the parameters of this one feature.
Okay ,that sound good, but if virTypedParameters can be passed to qemu_driver
such as qemu_monitor_json.c qemu_monitor_text.c ?
For virdomainMigrateSetParameters, if specifying a negative value to
level, threads, and dthreads parameters, such as -1, means do not set the
parameters.
The underlying code will not pass the corresponding parameters to qemu
monitor.
Such as threads and dthreads is -1, then pass the following json streaming to
qemu.
{ execute: migrate-set-parameters , arguments: {
compress-level: 1 } }
The virsh will expose the two commands:
# virsh migrate-setparameters domain [--level level] [--threads
threads] [--dthreads dthread] # virsh migrate-getparameters domain
2. How to enable multi-thread compression in application interface?
There is not a special interface for setting migration capabilities.
But we can set the capabilities when execute an virsh command as
following:
$ migrate --live] [--offline] [--p2p] [--direct] [--tunnelled]
[--persistent] [--undefinesource] [--suspend] [--copy-storage-all]
[--copy-storage-inc] [--change-protection] [--unsafe] [--verbose]
[--compressed] [--abort-on-error] domain desturi [migrateuri]
[graphicsuri] [listen-address] [dname] [--timeout number]
[--xml string]
There is already a compressed option, here compressed means xbzrle not
multi- compressed.
can I rename the compressed to xbzrle?
If we think that it is worth always turning on both compression styles
simultaneously, then reuse the bit. Otherwise, we need a different bit, and
users can choose which (or both) of the two compression styles as desired.
+1 for reuse compressed, and we can set compress-level, compress-threads,
compress-dthreads by virdomainMigrateSetParameters(maybe some new virsh
command--- migrate-setparameter)
But how can we passing these parameter when we using `virsh migrate `, is there
any parameter we can use in 'virsh migrate' command ?
Can you point me out ?
so we add another option for multi-thread compression, which is better option
name? -multi- compressed ?
Any way
Re: [libvirt] [RFC] libvirt support multi-thread compression for live migration
On 06/02/2015 07:56 AM, Qiao, Liyong wrote: Hi Eric Thanks for replying the mail, replied in lines. +virdomainMigrateGetParameters(virDomainPtr domain, + int *level, + int *threads, + int *dthreads, + int flags) + I'd rather we used virTypedParameters, to make it easier to use the same API to pass ALL future possible tuning parameters, rather than just hard-coding to only the parameters of this one feature. Okay ,that sound good, but if virTypedParameters can be passed to qemu_driver such as qemu_monitor_json.c qemu_monitor_text.c ? [Your quoting style makes it very hard to distinguish original text from added text. Please consider changing your outgoing mail process to ensure that you add another level of quoting to all previous text so that your added text is the only unquoted text. Also, configure your mailer to wrap long lines.] Use existing API for a guide - for example, virDomainSetBlockIoTune takes virTypedParamters, as well as defines a specific set of parameters that it will understand. The set of parameters can be enlarged without needing a new API (good for backporting features without requiring a .so version bump), but for any given libvirt version, the set of features understood is finite and limited to what you can translate to the QMP call. So qemu_driver.c would take the virTypedParameters, reject the ones it does not understand, and convert the ones it does understand into the 'int level, int threads, int dthreads' parameters used in qemu_monitor_json.c where you drive the actual QMP command with fixed parameters and types. If we think that it is worth always turning on both compression styles simultaneously, then reuse the bit. Otherwise, we need a different bit, and users can choose which (or both) of the two compression styles as desired. +1 for reuse compressed, and we can set compress-level, compress-threads, compress-dthreads by virdomainMigrateSetParameters(maybe some new virsh command--- migrate-setparameter) But how can we passing these parameter when we using `virsh migrate `, is there any parameter we can use in 'virsh migrate' command ? Can you point me out ? The underlying API already has a form that takes virTypedParameters (see virDomainMigrate3()), so your first task is to figure out how to extend the API to expose new typed parameters for your new migration tunings. Once that is done, then you can worry about how to tweak the 'virsh migrate' client to pass in those new parameters. -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
