linux-kernel - Re: XFS filesystem performance drop in kernels 2.6.16+

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 10 Nov 2006 22:52:57 -0800
From:	Andrew Morton <akpm@...l.org>
To:	"Igor A. Valcov" <viaprog@...il.com>
Cc:	linux-kernel@...r.kernel.org, xfs@....sgi.com
Subject: Re: XFS filesystem performance drop in kernels 2.6.16+

On Fri, 10 Nov 2006 16:16:27 +0300
"Igor A. Valcov" <viaprog@...il.com> wrote:

> Below is a simplified version of the test program,

Boy, I hope not.  The results of this test program are of very little interest.

>     for (i = 0; i < 262144; i++) {
>         /* Write data to a big file */
>         write (nFiles [0], buf, __BYTES);
> 
>         /* Write data to small files */
>         for (f = 1; f < __FILES; f++)
>             write (nFiles [f], &f, sizeof (f));
>     }

This sits in a loop doing write(fd, buf, 4).  This is wildly inefficient -
you'd get a 10x throughput benefit and maybe 100x reduction in CPU cost
simply by switching to fwrite().

I suspect something went wrong here.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/