Re: vmalloc - kmalloc and page locks

["Deas, Jim" <James.Deas@warnerbros.com>]

Thanks for the clarification. I am using mlockall on the user application. This 
still leaves me with the mystery of why my system usage goes from 3% to
50% randomly while playing data streams off the harddrive. I can also make
system usage stay at 50% by opening a third stream.
These streams are pulling data at 1.5MB/s each from different files (same HD).
I don't see that as a big strain on the hardware (4.5MB/s total data rate).
Where else should I look to find the bottleneck/latency issue?

Regards,
J. Deas


-----Original Message-----
From: Gábor Lénárt [mailto:lgb@lgb.hu]
Sent: Tuesday, July 22, 2003 6:13 AM
To: Deas, Jim
Cc: linux-kernel@vger.kernel.org
Subject: Re: vmalloc - kmalloc and page locks


Errrrr ... Sorry, I did not read your mail carefully ;-(
I meant in case of a user process you can use mlock() and such :)
AFAIK the kernel itself is not pagable ...

On Tue, Jul 22, 2003 at 03:07:18PM +0200, Gábor Lénárt wrote:
> Please read something about the mlock() and/or mlockall() functions.
> The prototype can be found in [/usr/include/]sys/mman.h
> You can read there:
> 
> /* Guarantee all whole pages mapped by the range [ADDR,ADDR+LEN) to
>    be memory resident.  */
> extern int mlock (__const void *__addr, size_t __len) __THROW;
> [...]
> /* Cause all currently mapped pages of the process to be memory resident
>    until unlocked by a call to the `munlockall', until the process exits,
>    or until the process calls `execve'.  */
> extern int mlockall (int __flags) __THROW;
> 
> On Tue, Jul 22, 2003 at 06:00:14AM -0700, Deas, Jim wrote:
> > How can I look at what memory are being paged out of memory in the kernel
> > or how to lock kmalloc and vmalloc pages so they do not get put to swap?
> [...]
> 
> - Gábor (larta'H)
> -
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-- 
- Gábor (larta'H)