From: Wu Fengguang <wfg@mail.ustc.edu.cn>
To: Alexandre Cassen <acassen@freebox.fr>
Cc: Ram Pai <linuxram@us.ibm.com>,
linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
slpratt@us.ibm.com, Con Kolivas <kernel@kolivas.org>,
Folkert van Heusden <folkert@vanheusden.com>
Subject: Re: [PATCH 2.6.14] Adaptive read-ahead V6
Date: Wed, 2 Nov 2005 15:23:15 +0800 [thread overview]
Message-ID: <20051102072315.GB4072@mail.ustc.edu.cn> (raw)
In-Reply-To: <Pine.LNX.4.61.0511012131290.20381@lnxos>
Hi, Alexandre,
On Tue, Nov 01, 2005 at 09:55:10PM +0100, Alexandre Cassen wrote:
> I just replayed a benchmark with your new patch. You will find attached
> new bench output.
>
> Experiment Protocol: . 10 mpeg2 video bit/rate=3.5Mb/s ATM
> . around 4Mb/s ip+udp per stream
> . Linux Kernel 2.6.14 + your v6 patch
> . stored on a raid0 /dev/md0 - XFS
> . blockdev --setra 2048 /dev/md0
> . 6GB RAM + 2*GiGE NICs Trunk +
> 2*36GB HDD on a U320 adaptec controler
> . R-A LOOKAHEAD_RATIO=4
> . ADP R-A /proc/sys/vm/readahead_ratio=200
> . Lauch video at true random positions
>
> I launched 20 clients per video, say 200 streams. I collected infos during
> around 1hours running.
>
> Let me know if you want some more inputs.
Thanks.
> [table requests] total newfile state context contexta backward onthrash onraseek none
> cache_miss 2847 6 1525 694 0 0 0 4 618
> read_random 295 2 3 2 0 0 0 0 288
> io_congestion 0 0 0 0 0 0 0 0 0
> io_cache_hit 7420 3 5941 1472 0 0 0 4 0
> io_block 4159 807 36 2648 0 0 0 4 664
This reflects times of IO delays.
The main delays(2648) occur in context method, which are triggered by cache misses(2847).
The cache misses might be caused by canceled look-ahead marks due to cache hits.
I'll try fixing it.
> readahead 116568 801 113031 2731 1 0 0 4 0
> lookahead 115904 223 112954 2726 1 0 0 0 0
> lookahead_hit 113376 31 111256 2072 1 0 0 0 16
> readahead_eof 660 578 77 5 0 0 0 0 0
> readahead_shrink 0 0 0 0 0 0 0 0 0
> readahead_thrash 0 0 0 0 0 0 0 0 0
> readahead_rescue 18517 0 0 0 0 0 0 0 18517
>
> [table pages] total newfile state context contexta backward onthrash onraseek none
> cache_miss 5452 6 3037 1377 0 0 0 7 1025
> read_random 391 2 5 2 0 0 0 0 382
> io_congestion 0 0 0 0 0 0 0 0 0
> io_cache_hit 622587 4 386637 235281 0 0 0 665 0
> io_block 547948 1954 1443 542863 0 0 0 1024 664
> readahead 28748734 1959 28414048 332302 66 0 0 359 0
> readahead_hit 28830698 1764 28414032 412507 3 0 0 856 1536
> lookahead 29202363 448 28780361 421521 33 0 0 0 0
> lookahead_hit 28671617 64 28358286 313232 35 0 0 0 0
> readahead_eof 15225 1065 13458 702 0 0 0 0 0
> readahead_shrink 0 0 0 0 0 0 0 0 0
> readahead_thrash 0 0 0 0 0 0 0 0 0
> readahead_rescue 265680 0 0 0 0 0 0 0 265680
Your system is memory bounty and thrashing free.
The ~1G rescued pages are expected to be saved for a following reader.
>
> [table summary] total newfile state context contexta backward onthrash onraseek none
> random_rate 0% 0% 0% 0% 0% 0% 0% 0% 99%
> ra_hit_rate 100% 90% 99% 124% 4% 0% 0% 237% 153600%
> la_hit_rate 97% 13% 98% 75% 50% 0% 0% 0% 1600%
> avg_ra_size 247 2 251 122 33 0 0 72 0
> avg_la_size 252 2 255 155 16 0 0 0 0
Regards,
Wu Fengguang
prev parent reply other threads:[~2005-11-02 7:23 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-01 13:49 Wu Fengguang
[not found] ` <Pine.LNX.4.61.0511012131290.20381@lnxos>
2005-11-02 7:23 ` Wu Fengguang [this message]
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