linux-kernel - 2.6.30-rc deadline scheduler performance regression for iozone over NFS

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-next>] [day] [month] [year] [list]

Date:	Thu, 23 Apr 2009 10:01:58 -0400
From:	Jeff Moyer <jmoyer@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Jens Axboe <jens.axboe@...cle.com>
Subject: 2.6.30-rc deadline scheduler performance regression for iozone over NFS

Hi,

I've been working on CFQ improvements for interleaved I/Os between
processes, and noticed a regression in performance when using the
deadline I/O scheduler.  The test uses a server configured with a cciss
array and 1Gb/s ethernet.

The iozone command line was:
  iozone -s 2000000 -r 64 -f /mnt/test/testfile -i 1 -w

The numbers in the nfsd's row represent the number of nfsd "threads".
These numbers (in MB/s) represent the average of 5 runs.

               v2.6.29

nfsd's  |   1    |  2   |   4   |   8
--------+---------------+-------+------
deadline| 43207 | 67436 | 96289 | 107590

              2.6.30-rc1

nfsd's  |   1   |   2   |   4   |   8
--------+---------------+-------+------
deadline| 43732 | 68059 | 76659 | 83231

    2.6.30-rc3.block-for-linus

nfsd's  |   1   |   2   |   4   |   8
--------+---------------+-------+------
deadline| 46102 | 71151 | 83120 | 82330

Notice the drop for 4 and 8 threads.  It may be worth noting that the
default number of NFSD threads is 8.

Cheers,
Jeff
--
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/