How can we test the efficiency of the features provided by the OSes like
Scheduling, Mem. Management, VM, network buffers (this i'm thinking to run
with some traffic generator tool).
I don't know about VxWorks but for the linux kernel take a look at ftrace.
-Joel
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To unsubscribe from this
If a kernel code requires an external loadable module then will it get
loaded automatically?
Yes it will be, after you install a module, depmod is run which
generates a file called modules.dep . modules.dep lists all
dependencies for every module. These dependencies are then
automatically
I'm sorry I misread your question. I guess the correct reason would be
/build/include/linux has a lot of header files that userspace programs
wouldn't need and are internal to the kernel.
Thanks for the reply!
but then what is the need for /usr/include/linux/*.h files ?
Hi Sid,
There are
On Sun, Jun 13, 2010 at 2:17 PM, vikas chauhan presentisg...@gmail.com wrote:
On 13 June 2010 14:31, vikas chauhan presentisg...@gmail.com wrote:
I guess these headers ( in /usr/include/linux ) are sanitized kernel
headers, needed for compiling user space applications.
Do not top post
I see in my system (Ubuntu Hardy) that linux header files are at two places
1. si...@siddu-desktop:/usr/include$ find
/lib/modules/2.6.24-16-generic/build/include/linux/ | wc -l
850
These headers are for compiling kernel code
2. si...@siddu-desktop:/usr/include$ find /usr/include/linux/ |
On Fri, Jun 11, 2010 at 7:41 PM, Joel Fernandes agnel.j...@gmail.com wrote:
I see in my system (Ubuntu Hardy) that linux header files are at two places
1. si...@siddu-desktop:/usr/include$ find
/lib/modules/2.6.24-16-generic/build/include/linux/ | wc -l
850
These headers are for compiling
I was looking at the SAVE_ALL code for kernel 2.6.
I am confused why SAVE_ALL restores __USER_DS to ds and es ?
#define SAVE_ALL \
cld; \
pushl %fs; \
pushl %es; \
pushl %ds; \
pushl %eax; \
pushl %ebp; \
pushl %edi; \
pushl
snip
since Linux doesn't use segmentation , all the segment descriptor values
are the same. So I think it doesn't matter what selector value you load in
DS, ES etc. Though I don't know the real reason for why __USER_DS is used
instead of __KERNEL_DS
Although, linux doesn't use
On Mon, Jun 07, 2010 at 05:28:51PM +1200, Simon Kitching wrote:
On Sun, 2010-06-06 at 13:49 +0530, Joel Fernandes wrote:
On Sun, Jun 6, 2010 at 3:06 AM, Vimal j.vi...@gmail.com wrote:
Hi Joel,
now i have a question, even if they share the same vm address space -
they definitely
On Sun, Jun 6, 2010 at 3:06 AM, Vimal j.vi...@gmail.com wrote:
Hi Joel,
now i have a question, even if they share the same vm address space -
they definitely can't share the userspace stack, i'm sure the kernel
would have to reset it up in the same address space of the group of
threads but
On Sat, Jun 5, 2010 at 3:54 PM, Joel Fernandes agnel.j...@gmail.com wrote:
Hi Robert,
If you are sure about constantly adding new material etc, then I think
a good idea would be to turn it into a subscription based service at
$3 / month or something (too less?), something like LWN. I know I
sorry, but that's just not going to happen. ever. if the general
impression here is that, for a donation of five bucks, you expect to
get unfettered access to my personal attention, then we have massively
different views of how the world works.
Well, 5 bucks was just an example. You can
On Sat, Jun 5, 2010 at 3:20 PM, Joel Fernandes agnel.j...@gmail.com wrote:
On Sat, Jun 5, 2010 at 11:14 AM, Vimal j.vi...@gmail.com wrote:
On 4 June 2010 17:16, Group mailforgr...@gmail.com wrote:
Hi,
Is it possible to access threads stack (not shared) from another thread?
I have seen an API
I'm learning block devices in Linux. It seems submit_bio can be used by file
systems to submit block IO requests. But after I search for it in the linux
kernel, I didn't see file systems like ext2 and ext3 use it. So how does a
file
system usually submit a request? I didn't find a wrapper of
Hi Michi,
On Mon, May 24, 2010 at 10:29 PM, Michael Blizek
mic...@michaelblizek.twilightparadox.com wrote:
Hi!
On 22:53 Mon 24 May , Mulyadi Santosa wrote:
On Mon, May 24, 2010 at 18:03, Michael Blizek
mic...@michaelblizek.twilightparadox.com wrote:
Hi!
I have a system with 32 bit
Hi Mayank,
Depending on the device, you can use sysfs (/sys) for this.
Your email address says utexas, are you currently studying at a uni in
texas? I'm joining CS this fall at UTDallas =)
cheers,
Joel
On Wed, May 19, 2010 at 3:44 AM, Mayank Kaushik mayank.ute...@gmail.com
wrote:
Hi
Just forwarding to the list
-- Forwarded message --
From: Joel Fernandes agnel.j...@gmail.com
Date: Tue, May 4, 2010 at 12:40 PM
Subject: Re: System memory increased while process is running is not
released back upon process exit
To: ravikumar ravikumar.valla...@gmail.com
Hi
Hey Venkatram,
On Wed, Apr 28, 2010 at 11:33 AM, Venkatram Tummala
venkatram...@gmail.comwrote:
to find these addresses by p modules, the module has to be already
loaded.right? So, the initialization function of the module must have
been already executedright? So, the question is how
On Tue, Apr 27, 2010 at 7:55 AM, rahul patil
rahul.deshmukhpa...@gmail.comwrote:
Though it is bad idea to call a system call from kernel space
is it possible any how to call a system call from kernel space?
Generally a better idea to user kernel interfaces directly instead of sys
calls.
On Wed, Apr 28, 2010 at 8:09 AM, Joel Fernandes agnel.j...@gmail.comwrote:
On Tue, Apr 27, 2010 at 7:55 AM, rahul patil
rahul.deshmukhpa...@gmail.com wrote:
Though it is bad idea to call a system call from kernel space
is it possible any how to call a system call from kernel space
On Wed, Apr 28, 2010 at 8:35 AM, rahul patil rahul.deshmukhpa...@gmail.com
wrote:
i want to call open,write system calls from kernel space.
[oops, didn't hit reply-to-all at first, sorry rahul!]
Not sure about open, but for read/write system calls, provided you already
have file opened and
Hi Robert,
for debugging purposes, is it even physically possible to compile
the kernel with no optimization whatever?
Why wouldn't it be?
Thanks,
-Joel
On Mon, Apr 19, 2010 at 5:43 AM, Mulyadi Santosa
mulyadi.sant...@gmail.comwrote:
Hi Robert
On Mon, Apr 19, 2010 at 02:48, Robert P. J. Day rpj...@crashcourse.ca
wrote:
for debugging purposes, is it even physically possible to compile
the kernel with no optimization whatever?
IMO,
Could anyone explain the significance of the BH_Boundary flag in a
buffer head. and when you should this flag be set or cleared?
What other effects does setting or clearing this flag have?
Thanks,
Joel
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To unsubscribe from this list: send an email with
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On Thu, Apr 8, 2010 at 11:34 AM, Joel Fernandes agnel.j...@gmail.com
wrote:
Could anyone explain the significance of the BH_Boundary flag in a
buffer head. and when you should this flag be set or cleared?
What other effects does setting or clearing this flag have?
Set if the block
I wish we could use mmap in kernel space but I think its hard to implement
this, all kernel memory is directly and permanently mapped and not
swappable. You can vmalloc in kernel but you cannot mmap..
Sorry I went wrong there, what I meant was you cannot have a page fault
trigger on kernel
Hi Venkatram,
thanks for your wonderful explanation, I delayed asking further questions
till I read every ones posts, its much clearer now. :)
To make things clear, 896 MB is not a hardware limitation. The 3GB:1GB split
can be configured during the kernel build but the split cannot be changed
Hi Hayfeng,
On Tue, Apr 6, 2010 at 8:07 PM, hayfeng Lee teklife.ker...@gmail.com wrote:
hello,every one.
I have a question:
Why does linux choose 896MB to do a start point of ZONE_HIGHMEM and
the end point of ZONE_NORMAL. Just for experience?
What is the advantages?
This is not an advantage
Hi Peter,
On Wed, Apr 7, 2010 at 1:14 AM, H. Peter Anvin h...@zytor.com wrote:
On 04/06/2010 12:20 PM, Frank Hu wrote:
The ELF ABI specifies that user space has 3 GB available to it. That
leaves 1 GB for the kernel. The kernel, by default, uses 128 MB for I/O
mapping, vmalloc, and kmap
Hi Greg,
Instead there is an intermediary context that I don't think you've
taken into account.
I believe timers are also invoked in this intermediary context. ie.
When a timer invokes a function you can't trust the process / task
structures to relate to your original userspace app.
I
Like for example when a write() happens, this doesn't have to
necessarily go all the way till the disk immediately, instead its
Ofcourse, unless the file is opened in O_DIRECT mode
-Joel
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My understanding is the kernel uses interrupts to count the time and to
trigger timer routines - but these routine are executed in the context they
were registered. A timer created by a process executes in process
context. A driver registered timer executes in kernel context (not interrupt).
Hi Greg,
I'm relatively new to this stuff but I think I will make some bold statements:
With linux today, is there a specific process context (ie. kernel
thread) associated with executing functions triggered by timers firing
off?
No, a timer being fired wouldn't be associated with any single
As a part of 2.6 kernel compilation I want to include my module to
make static module.
What do you mean by static module? Do you mean you want to make it a
part of the kernel image?
All modules are supposed to be relocatable so that they can be loaded
in any part of kernel memory on insmod.
Hi Stephan,
I'm no expert this is what I think:
1. What event awakes the process? Has the driver any way to control it?
The kernel code executing on behalf of the process is usually waiting
for some resource to become available, we sleep because we can't
return from the middle and have to wait
, Joel Fernandes agnel.j...@gmail.com wrote:
In fact the kernel is not interrupt-able in linux as I recall. Thus
a misbehaving driver that enters an infinite loop will hang the whole
machine.
...
Another way to ask your question is Why isn't the linux kernel itself
timesliced?
AFAIK, What you're
My understanding is in a driver:
- use schedule() when waiting for kernel services.
- use timers when waiting for the device.
Hi Stephan,
You got it all right except the fact that you cannot use a timer
because timers execute in interrupt context, not process context.
When your Process
Makefile determine which file will be compiled.
Makefile also determines which objects are linked together to produce
your final relocatable kernel module.
But how does the kernle finally know what is the name of module and
The module name comes IMO from the final object-name.ko.
how many
But how does the kernle finally know what is the name of module and
The module name comes IMO from the final object-name.ko.
More precisely the module name is specified in the Makefile.
For example for the ext2 kernel module, the ext2-y and ext2.o
entries in the Makefile tells the kernel build
Its so quite in hear (maybe because of Ash wednesday?) so I thought
I'd break the silence with a few questions. :)
I've been reading about the block layer and the scatter gather
mechanism which uses an array of bio_vecs in a single bio.
My questions are:
1. Can a particular bio vector (segment)
Hi Neependra,
My question is, Is there a better way (better than logging) of
tracking operations internal to the kernel continuously over long
period of time in a way that doesn't affect latency (very
drastically)?
You can look at SystemTap which has very less overhead.
On Sat, Jan 30, 2010 at 3:59 AM, Joel Fernandes agnel.j...@gmail.com wrote:
My question is, Is there a better way (better than logging) of
tracking operations internal to the kernel continuously over long
period of time in a way that doesn't affect latency (very
drastically)?
Maybe you also
I've made some changes to ext2 filesystem, and its approaching
stability but not yet there.
The problem is that I see corruptions after the FS has been mounted
and running for days, but not immediately.
The other problem is these corruptions don't show up on our test
environment, and only on
, 2010 at 12:20 PM, Joel Fernandes agnel.j...@gmail.com
wrote:
Incase it helps some one else, I upgraded from gdb-6.8 to gdb 7.0 and
the line numbers show up fine.
hmff, bug in DWARF reading
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog
PM, Joel Fernandes agnel.j...@gmail.com wrote:
I think the problems were in the way the line information was
structured in the kernel module ELF.
The line information of all the objects were clubbed together when
compiling for x86_64 but the starting numbers were not taken into
account
Nice observation :) So, perhaps might question, what the best way to
avoid such problem. always use latest gdb? I thought things like
this is formally standardized
I don't know why ld resets the addresses (or rather doesn't make the
addresses continugous in .debug_line) when linking
perhaps we can peek into ksplice on how to deal with such thing? i
haven't used ksplice by myself, but I guess it will use DWARF info
somehow, right?
Sure, there's also elfutils (readelf is a part of that) which contains
code that parses dwarf line info.. but line info is fairly
non-trivial,
of the per-cpu variable
current_task work in the above code?
Thanks,
-Joel
On Tue, Jan 26, 2010 at 12:43 PM, Robin Randhawa
robin.randh...@gmail.com wrote:
Hi Joel.
On Tue, Jan 26, 2010 at 03:23:03AM +0530, Joel Fernandes wrote:
I am having some trouble accessing 'current' to get the currently
modprobe is smart and knows what modules support what devices based on
the cache it creates when you run 'depmod' when a new kernel is
installed.
That information is found in the drivers themselves.
See the modprobe code for details if you wish to know the exact
mechanisms involved, it's
Hi Greg.
What you want to look at is the modules.alias file. That is what makes
things so simple, it creates a mapping from a device/product id to the
actual module.
I get the idea now, thanks. So when a device is connected, a modalias
is generated with the vendor/productid and then modprobe
I am having some trouble accessing 'current' to get the currently
executing task in kgdb (x86_64).
As current is a macro, I can't expand it in kgdb, so instead I'm
trying to access the variable per_cpu__current_task inorder to get the
task_struct for the currently executing task. But the memory
On Sun, Jan 24, 2010 at 12:57 PM, ZelluX zel...@gmail.com wrote:
So actually dynamic linking has nothing to do with kernel, or there's no
special system calls or other mechanisms provided by kernel to support
dynamic linking, is it right?
Why would you need special support in the kernel? As
Incase it helps some one else, I upgraded from gdb-6.8 to gdb 7.0 and
the line numbers show up fine.
Thanks,
-Joel
On Wed, Jan 20, 2010 at 2:08 PM, Mulyadi Santosa
mulyadi.sant...@gmail.com wrote:
Hi...
On Tue, Jan 19, 2010 at 10:14 PM, Joel Fernandes agnel.j...@gmail.com wrote
I have a doubt with the modalias file in sysfs and its role in
modprobe's ability to automatically load modules.
I understand that this file is generated by the kernel based on the
list of devices that the driver tells the kernel it supports?
and it is with this list that modprobe figures which
I wrote a bit about dynamic linking and ELF a while back too,
Maybe you can find something useful:
http://www.hackerbliss.org/2009/11/notes-on-elf-file-format.html
-Joel
On Sat, Jan 23, 2010 at 10:38 AM, ZelluX zel...@gmail.com wrote:
Really useful book and article, many thanks for your replies
then this function
* becomes a no-operation.
*/
int __request_module(bool wait, const char *fmt, ...)
{
On Sat, Jan 23, 2010 at 7:04 PM, Joel Fernandes agnel.j...@gmail.com
wrote:
I have a doubt with the modalias file in sysfs and its role in
modprobe's ability to automatically load modules
I am trying to debug a kernel module that has been loaded after the start of
a kgdb session.
Once I load the module, I do:
(gdb) add-symbol-file ~/ext2.ko 0xa01b1000
This works fine, and gdb knows the addresses of the symbols in the kernel
module, to verify this:
At the KGDB target:
#
Hi Mulyadi, thanks for your message as always :) Just some thoughts:
But why doesn't gdb load it when I do an 'add-symbol-file' ? What am I doing
wrong here?
I guess, kgdb stub in the target's end doesn't implement complete
DWARF readingspecificly address to line numbers translation.
On Wed, Jan 20, 2010 at 8:43 AM, Tony Miller mcfiredr...@gmail.com wrote:
Is it possible to browse the kernel source with ctags? I used
exuberant-ctags to generate a tags file for my kernel sources, but it
doesn't really work as you expect. If you try to jump to the definition of a
function it
Yes.
Do a quick grep for functions calling do_fork in arch/x86/kernel/*
-Joel
On Sat, Jan 16, 2010 at 10:40 PM, Daniel (Youngwhan) Song
breadn...@gmail.com wrote:
Thank you, Mulyadi, now, I could understand about NPTL implementation and
lightweight process concept.
One thing I want to check
The CLONE_KERNEL flag is defined as:
#define CLONE_KERNEL(CLONE_FS | CLONE_FILES | CLONE_SIGHAND)
So as I understand it, when the CLONE_KERNEL flag is passed at the
time of creating a kernel thread, the copy_process function copies the
file descriptors and signal handlers from the currently
Why is preemption disabled before a lock is acquired in _spin_lock function?
As the critical region of code which is to be protected by the spin
lock executes only after the lock is acquired, why is disabling of
preemption required before the lock is acquired?
Wouldn't it better if the kernel
Thanks for your message.
Also adding to that, I think it doesn't matter because spinlocks are
supposed to held for a short period.
-Joel
On Sun, Jan 17, 2010 at 10:13 PM, Mulyadi Santosa
mulyadi.sant...@gmail.com wrote:
Hi Joel...
On Sun, Jan 17, 2010 at 9:34 PM, Joel Fernandes agnel.j
Hi,
The book Linux Kernel Development mentions a certain overhead which is
reduced in linux because the child is made to run first after it is
forked (instead of the parent) and if the child executes the exec
system call.
Quoting Pg 32 (2nd edition):
In do_fork() the child is woken up and run.
How does running exec() in child more efficient than having
copy-on-write trigger in the parent?
In order to create a new process (fork), you will copy the whole of
relevant info of address space from the parent. Now if the address
space is shared and parent runs first for any change it
this copying so it can't be avoided in any
case. The book says copy-on-write itself has more overhead that is
avoided with exec() in the child, but I'm trying to figure how.
-Joel
On Mon, Jan 11, 2010 at 12:18 AM, Manish Katiyar mkati...@gmail.com wrote:
On Mon, Jan 11, 2010 at 12:02 AM, Joel
wrote:
On Wed, Jan 6, 2010 at 4:20 AM, Joel Fernandes agnel.j...@gmail.com wrote:
There is a certain hashtable that I am currently implementing in the
kernel using file handling for sake of persistence. It is actually a
file-based binary tree (nodes are referred to by file offsets instead
Hi Manish, Mulyadi,
Yes I see it now, Thanks for your help.
-Joel
On Mon, Jan 11, 2010 at 6:22 AM, Mulyadi Santosa
mulyadi.sant...@gmail.com wrote:
On 1/11/10, Joel Fernandes agnel.j...@gmail.com wrote:
Oh I'm sorry, if you were talking about copying of the address space
information that can
As there are many changes in Latest kernel with respect to LDD3
documentation.so where can i get documentation of latest API and which API
and flags deprecated with respect to LDD3.
The kernel interfaces are themselves sort of well documented in the sources.
I usually search LKML
if you just want a dev board to get started, why not go with a
beagleboard?
http://beagleboard.org/
Most of these boards have export restrictions for 3rd world countries
and getting a clearance is beyond individual or group thing needs
more force :)
If you're talking about India,
There is a certain hashtable that I am currently implementing in the
kernel using file handling for sake of persistence. It is actually a
file-based binary tree (nodes are referred to by file offsets instead
of memory addresses). The problem is that the tree can get unbalanced
quite quickly and
compiled with the kernel?
Thanks,
-Joel
On 12/30/09, Mulyadi Santosa mulyadi.sant...@gmail.com wrote:
Hi Joel...
I hope you don't mind that I rewrite the subject to avoid confusion...
On Wed, Dec 30, 2009 at 11:12 AM, Joel Fernandes agnel.j...@gmail.com
wrote:
Hey Mulyadi,
It acts as initial
Hey Mulyadi,
It acts as initial root filesystem containing modules needed to
proceed into complete successful booting e.g loading ext3 kernel
module to access real filesystem, loading LVM modules in case your
root filesystem stays inside LVM etc etc
My root file system is ext3 and I have it
inird:
http://www.ibm.com/developerworks/linux/library/l-initrd.html
http://en.wikipedia.org/wiki/Initrd
ramdisk:
http://www.vanemery.com/Linux/Ramdisk/ramdisk.html
In recent times, ramdisk in the context of an initrd is really a
misnomer and is more accurately an initramfs - cpio archive that
Am I right in saying that there is kernel mode stack maintained per
process?
Yes.
Also in the book Understanding the Linux Kernel in chapter 3:
Processes there is a diagram of the stack and the thread_info structure. The
addresses shown are 0x015fa000 etc. Shouldn't the addresses start
Hi Mulyadi,
Thanks for your response. But, DMA doesn't happen to the stack so its
ok if the (2-page)stack is not physically contiguous as long as it is
virtually contiguous?
I'm talking in terms of the processor architecture where all memory
accesses are infact virtual when paging
is turned on,
There was a requirement in older kernels that the stack (which was
then 2 pages and is now 1 page in newer kernels) had to be physically
adjacent.
Why was there such a requirement? wouldn't it have sufficed for the
kernel stack to be contiguous in virtual memory?
Thanks,
-Joel
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To unsubscribe
, 2009 at 5:48 PM, Joel Fernandes agnel.j...@gmail.com
wrote:
There was a requirement in older kernels that the stack (which was
then 2 pages and is now 1 page in newer kernels) had to be physically
adjacent.
Why was there such a requirement? wouldn't it have sufficed for the
kernel stack
Hi Peter,
There is always something new to learn from your posts. thanks :)
Regards,
Joel
On Mon, Dec 7, 2009 at 8:44 AM, Peter Teoh htmldevelo...@gmail.com wrote:
On Sun, Dec 6, 2009 at 5:57 AM, Herlin R. Matos Lastres
hma...@grm.uci.cu wrote:
Hi,
I need manage the keyboard, for example
My question is why the cache is growing even after O_SYNC flag? Even
fsync does not help. But deleting file freeing the cache.
Try O_DIRECT if you want to bypass the page cache.
-Joel
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Actually, IMO, even on 2.4, loosely replacing certain or all
sys_call_table entries are highly discouraged. The reason is
similar...you don't know whether they are currently referenced or not,
right?
Since all other code expects it to be read-only anyway once its setup
(if I'm right),
You have not used ret instruction in AsmFn2, I guess it will cause
undefined behavior. I think it has nothing to do with how you compile
the code. It works perfectly after adding ret instruction at the end
of AsmFn2. Correct me if I am missing something here.
Thanks. That was the problem,
Yes that's right, AFAIK kmap allocates physically contiguous memory
and vmalloc allocates virtual contiguous memory.
Sorry, change kmap to kmalloc.
Regards,
-Joel
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Please read the FAQ at
Thanks for your replied. I surveyed in the internet and found the
kerenl's kmalloc API also return a continuous memory address. Is it
right? So there are two kernel APIs (__get_free_page, kmalloc) return
a _continuous_ memory address (virtual address) and it can be convert
to physical address
Try kscope, it is a source code browser (based on cscope) and an inline
editor (based on kate). It can also generate call graphs and stuff.
-Joel
On Tue, Nov 10, 2009 at 11:38 AM, Pulkit Goel vipulkit.g...@gmail.comwrote:
*Hi* Everyone,
1) I want to browse the linux *Kernel Source Code*
My questions:
1. Why wouldn't the kernel create a buffer page even for pages that contain
physically adjacent blocks? Why are pages that contain physically adjacent
blocks given special treatment?
I'm sorry I meant- why are pages that don't contain physical adjacent blocks
given special
Hi Mulyadi, I will just add a few more questions, don't mind me poking
in a bit.. :)
I think it's not the virtual address that is created, but the Virtual
Memory Area. Then, addresses are assigned to this VMA. Whether the VMA
contains page frame or not, that's another case.
Do you mean VMA of
Please help me to figure out some basic concepts in MM.
From the books, i learned that VMA to PA translation consists of traversing
the full page directory, which consists of Global Directory, Middle
Directory and Page Table.
I have also read that, VMA to PA translation is done using a
, Joel Fernandes wrote:
In data=ordered mode the ext3_ordered_commit_write function marks the
buffers as dirty, how then does the JBD ensure that the data is
written before the metadata? Once the data buffers are marked as
dirty, JBD doesn't have control anymore over when the data is written
Hi Vikram,
There are a lot of good books you can read:
http://www.amazon.com/Linux-System-Kernel-Programming-Books/lm/2ZE3JEGU41LP7
Robert Love's Linux Kernel Development is brief and nice, David
Bovet's Understanding the linux kernel dissects the internals of the
kernel in pain staking detail.
In data=ordered mode the ext3_ordered_commit_write function marks the
buffers as dirty, how then does the JBD ensure that the data is
written before the metadata? Once the data buffers are marked as
dirty, JBD doesn't have control anymore over when the data is written
is actually written to disk
Hi Robert,
Unfortunately I will not be able to attend it, are videos going to be
made available later? Is there anyway we can catch it live?
Good luck with the session.
Thanks,
Joel
On Wed, Oct 21, 2009 at 9:05 AM, Robert P. J. Day rpj...@crashcourse.ca wrote:
http://onlinux.ca/
and this
Hi Rajat,
So kernel virtual memory is always directly and permanently mapped and
never has to fault? Is this for performance or is it because the
kernel can't handle its own faults (kernel doesn't want to take
responsibility for its own faults!).
Also I would be grateful if you could describe in
Thanks for sharing! Peter, I think spindle is used just as another
word for slow device which I guess could be any other type of slow
storage medium like iSCSI or loop over NFS.
In some degree, I agree with that.
However, specificly to block device like hard disk, where things could
made
IMO yes, but starved better :) Not sure if I write it correctly, but
here is my understanding:
say you have 4 pdflush threads, competing to write to a disk. All are
busy, so you can say all are quite starved. But the writing process
(even though it's using async style) doesn't know about it.
Hi List,
I'm having a little problem with controlling logging levels.
Here I've set console_loglevel to 1 as shown below:
cat /proc/sys/kernel/printk
1 4 1 7
But /proc/kmsg still shows messages with lower priority levels such as
KERN_INFO and KERN_DEBUG with 6 and 7 tagged to
Ok seems I didn't read the docs carefully enough, seems
console_loglevel controls the level of logging to the console and not
to what klogd retrieves from the kernel log buffers. Correct?
Thanks,
-Joel
On Sun, Oct 18, 2009 at 12:45 AM, Joel Fernandes agnel.j...@gmail.com wrote:
Hi List,
I'm
On Sun, Oct 18, 2009 at 1:08 AM, Joel Fernandes agnel.j...@gmail.com wrote:
Ok seems I didn't read the docs carefully enough, seems
console_loglevel controls the level of logging to the console and not
to what klogd retrieves from the kernel log buffers. Correct?
I've managed to have syslog
On Sun, Oct 18, 2009 at 9:17 AM, Peter Teoh htmldevelo...@gmail.com wrote:
On 10/18/09, Rik van Riel r...@nl.linux.org wrote:
Peter Teoh wrote:
now the pdflush is deprecated by per-bdi writeout. Can I know
conceptually, in a few sentences, what are the key features that
enable per-bdi
to get along with it.
Joel Fernandes schrieb:
From fs/partitions/Makefile, it seems that atari partitions can be
compiled as a kernel module.
You also wouldn't need to recompile the kernel just for this.
Why do you think that? The Makefile says:
obj-$(CONFIG_ATARI_PARTITION) += atari.o
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