Re: vmalloc - kmalloc and page locks

From: Deas, Jim (James.Deas_at_warnerbros.com)
Date: 07/22/03

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    Date:	Tue, 22 Jul 2003 06:57:26 -0700
To: linux-kernel@vger.kernel.org

    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)
-
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