Re: [Qemu-devel] [v7 Patch 4/5]Qemu: Add commandline -drive option 'hostcache'

2011-10-14 Thread Supriya Kannery 

On 10/12/2011 08:00 PM, Kevin Wolf wrote:

Am 11.10.2011 05:11, schrieb Supriya Kannery:

qemu command option 'hostcache' added to -drive for block devices.
While starting a VM from qemu commandline, this option can be used
for setting host cache usage for block data access. Simultaneous
use of 'hostcache' and 'cache' options not allowed.

Signed-off-by: Supriya Kannerysupri...@linux.vnet.ibm.com


I'm not sure if introducing this alone makes sense. I think I would only
do it when we introduce more options that allow replacing all cache=...
options by other parameters.



Can we do transition to alternatives for 'cache=' in a phased manner?
Until all other params are ready, we can allow hostcache (as well
as other params as and when they are ready) in cmdline with the
condition that 'cache=x', if specified, overrides these params.
Once we have all other params ready, 'cache=' can be replaced completely.

thanks, Supriya

Re: [Qemu-devel] [v7 Patch 4/5]Qemu: Add commandline -drive option 'hostcache'

2011-10-14 Thread Kevin Wolf 
Am 14.10.2011 13:19, schrieb Supriya Kannery:
 On 10/12/2011 08:00 PM, Kevin Wolf wrote:
 Am 11.10.2011 05:11, schrieb Supriya Kannery:
 qemu command option 'hostcache' added to -drive for block devices.
 While starting a VM from qemu commandline, this option can be used
 for setting host cache usage for block data access. Simultaneous
 use of 'hostcache' and 'cache' options not allowed.

 Signed-off-by: Supriya Kannerysupri...@linux.vnet.ibm.com

 I'm not sure if introducing this alone makes sense. I think I would only
 do it when we introduce more options that allow replacing all cache=...
 options by other parameters.

 
 Can we do transition to alternatives for 'cache=' in a phased manner?
 Until all other params are ready, we can allow hostcache (as well
 as other params as and when they are ready) in cmdline with the
 condition that 'cache=x', if specified, overrides these params.
 Once we have all other params ready, 'cache=' can be replaced completely.

I guess that would be good enough. There's still not much use in
specifying hostcache=... at the same time as cache=... but at least it
doesn't take away other options then.

Kevin

Re: [Qemu-devel] [v7 Patch 4/5]Qemu: Add commandline -drive option 'hostcache'

2011-10-12 Thread Kevin Wolf 
Am 11.10.2011 05:11, schrieb Supriya Kannery:
 qemu command option 'hostcache' added to -drive for block devices.
 While starting a VM from qemu commandline, this option can be used 
 for setting host cache usage for block data access. Simultaneous
 use of 'hostcache' and 'cache' options not allowed.
 
 Signed-off-by: Supriya Kannery supri...@linux.vnet.ibm.com

I'm not sure if introducing this alone makes sense. I think I would only
do it when we introduce more options that allow replacing all cache=...
options by other parameters.

 
 ---
  blockdev.c  |   13 +
  qemu-config.c   |4 
  qemu-options.hx |2 +-
  3 files changed, 18 insertions(+), 1 deletion(-)
 
 Index: qemu/blockdev.c
 ===
 --- qemu.orig/blockdev.c
 +++ qemu/blockdev.c
 @@ -237,6 +237,7 @@ DriveInfo *drive_init(QemuOpts *opts, in
  DriveInfo *dinfo;
  int snapshot = 0;
  int ret;
 +int hostcache = 0;
  
  translation = BIOS_ATA_TRANSLATION_AUTO;
  media = MEDIA_DISK;
 @@ -319,7 +320,19 @@ DriveInfo *drive_init(QemuOpts *opts, in
   }
  }
  
 +if ((hostcache = qemu_opt_get_bool(opts, hostcache, -1)) != -1) {
 +if (!hostcache) {
 +bdrv_flags |= BDRV_O_NOCACHE;
 +} else {
 +bdrv_flags = ~BDRV_O_NOCACHE;
 +}

bdrv_flags is initialised to 0, so the else branch is unnecessary.

Kevin

[Qemu-devel] [v7 Patch 4/5]Qemu: Add commandline -drive option 'hostcache'

2011-10-10 Thread Supriya Kannery 
qemu command option 'hostcache' added to -drive for block devices.
While starting a VM from qemu commandline, this option can be used 
for setting host cache usage for block data access. Simultaneous
use of 'hostcache' and 'cache' options not allowed.

Signed-off-by: Supriya Kannery supri...@linux.vnet.ibm.com

---
 blockdev.c  |   13 +
 qemu-config.c   |4 
 qemu-options.hx |2 +-
 3 files changed, 18 insertions(+), 1 deletion(-)

Index: qemu/blockdev.c
===
--- qemu.orig/blockdev.c
+++ qemu/blockdev.c
@@ -237,6 +237,7 @@ DriveInfo *drive_init(QemuOpts *opts, in
 DriveInfo *dinfo;
 int snapshot = 0;
 int ret;
+int hostcache = 0;
 
 translation = BIOS_ATA_TRANSLATION_AUTO;
 media = MEDIA_DISK;
@@ -319,7 +320,19 @@ DriveInfo *drive_init(QemuOpts *opts, in
}
 }
 
+if ((hostcache = qemu_opt_get_bool(opts, hostcache, -1)) != -1) {
+if (!hostcache) {
+bdrv_flags |= BDRV_O_NOCACHE;
+} else {
+bdrv_flags = ~BDRV_O_NOCACHE;
+}
+}
+
 if ((buf = qemu_opt_get(opts, cache)) != NULL) {
+if (hostcache != -1) {
+error_report('hostcache' and 'cache' cannot co-exist);
+return NULL;
+}
 if (bdrv_parse_cache_flags(buf, bdrv_flags) != 0) {
 error_report(invalid cache option);
 return NULL;
Index: qemu/qemu-options.hx
===
--- qemu.orig/qemu-options.hx
+++ qemu/qemu-options.hx
@@ -135,7 +135,7 @@ DEF(drive, HAS_ARG, QEMU_OPTION_drive,
[,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n

[,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n
[,serial=s][,addr=A][,id=name][,aio=threads|native]\n
-   [,readonly=on|off]\n
+   [,readonly=on|off][,hostcache=on|off]\n
 use 'file' as a drive image\n, QEMU_ARCH_ALL)
 STEXI
 @item -drive @var{option}[,@var{option}[,@var{option}[,...]]]
Index: qemu/qemu-config.c
===
--- qemu.orig/qemu-config.c
+++ qemu/qemu-config.c
@@ -85,6 +85,10 @@ static QemuOptsList qemu_drive_opts = {
 .name = readonly,
 .type = QEMU_OPT_BOOL,
 .help = open drive file as read-only,
+},{
+.name = hostcache,
+.type = QEMU_OPT_BOOL,
+.help = set or reset hostcache (on/off)
 },
 { /* end of list */ }
 },