[4719] in linux-scsi channel archive
Disk I/O cache
daemon@ATHENA.MIT.EDU (Johns Daniel)
Mon Sep 21 13:13:48 1998
From: Johns Daniel <jdaniel@SYSTRAN.com>
To: "'linux-scsi@vger.rutgers.edu'" <linux-scsi@vger.rutgers.edu>
Date: Mon, 21 Sep 1998 11:16:12 -0400
[This is really a Linux kernel issue, but since some of
the block-device experts are hanging out here I thought I
would first try this list out!]
The Linux kernel caches disk I/O buffers in unused
physical memory. Normally this is good, but I have an
application in which this feature is a detriment to
performance. I am using Linux 2.1.122 (SMP). I have 256 MB
of RAM and ~380 MB of swap space. Although my program may
only need ~150 MB of memory, xosview shows ~250 MB of
memory being used, and also some paging activity going on.
The paging activity causes severe performance degradation.
[If I change the program parameters so that only less than
64 MB of memory is needed, my program runs _much_ faster.]
My program reads in sequential chunks (1 to 256 KB) of data
from one file, processes the data, and writes it out to
another file. Total filesize may be anything up to 2 GB.
Clearly, I do not need the read or write buffers cached
beyond a single access. Is there any way to let this be
known to the kernel? I.e., advise the kernel regarding
usage pattern?
Any other bright ideas?
Thank you ... Johns
========================================================
Johns Daniel, Sr Software Engineer jdaniel@systran.com
(937) 252-5601 x365 Fax (937) 252-1392
Systran Federal Corp, 4126 Linden, Dayton, OH 45432, USA
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.rutgers.edu
