From: "Jon Nelson" <jnelson@jamponi.net>
To: Bill Davidsen <davidsen@tmr.com>
Cc: Justin Piszcz <jpiszcz@lucidpixels.com>, linux-raid@vger.kernel.org
Subject: Re: Reading takes 100% precedence over writes for mdadm+raid5?
Date: Sat, 8 Dec 2007 18:13:26 -0600 [thread overview]
Message-ID: <cccedfc60712081613t78451d3fm97ea782eef2be0ec@mail.gmail.com> (raw)
In-Reply-To: <47581F2E.7020400@tmr.com>
This is what dstat shows me copying lots of large files about (ext3),
one file at a time.
I've benchmarked the raid itself around 65-70 MB/s maximum actual
write I/O so this 3-4MB/s stuff is pretty bad.
I should note that ALL other I/O suffers horribly, even on other filesystems.
What might the cause be?
I should note: going larger in stripe_cache_size (384 and 512)
performance stays the same, going smaller (128) performance
*increases* and stays more steady to 10-13 MB/s.
----total-cpu-usage---- --dsk/sda-- --dsk/sdb-- --dsk/sdc--
--dsk/sdd-- -dsk/total->
usr sys idl wai hiq siq| read writ: read writ: read writ: read
writ: read writ>
1 1 95 3 0 0| 12k 4261B: 106k 125k: 83k 110k: 83k
110k: 283k 348k>
0 5 0 91 1 2| 0 0 :2384k 4744k:2612k 4412k:2336k
4804k:7332k 14M>
0 4 0 91 1 3| 0 0 :2352k 4964k:2392k 4812k:2620k
4764k:7364k 14M>
0 4 0 92 1 3| 0 0 :1068k 3524k:1336k 3184k:1360k
2912k:3764k 9620k>
0 4 0 92 1 2| 0 0 :2304k 2612k:2128k 2484k:2332k
3028k:6764k 8124k>
0 4 0 92 1 2| 0 0 :1584k 3428k:1252k 3992k:1592k
3416k:4428k 11M>
0 3 0 93 0 2| 0 0 :1400k 2364k:1424k 2700k:1584k
2592k:4408k 7656k>
0 4 0 93 1 2| 0 0 :1764k 3084k:1820k 2972k:1796k
2396k:5380k 8452k>
0 4 0 92 2 3| 0 0 :1984k 3736k:1772k 4024k:1792k
4524k:5548k 12M>
0 4 0 93 1 2| 0 0 :1852k 3860k:1840k 3408k:1696k
3648k:5388k 11M>
0 4 0 93 0 2| 0 0 :1328k 2500k:1640k 2348k:1672k
2128k:4640k 6976k>
0 4 0 92 0 4| 0 0 :1624k 3944k:2080k 3432k:1760k
3704k:5464k 11M>
0 1 0 97 1 2| 0 0 :1480k 1340k: 976k 1564k:1268k
1488k:3724k 4392k>
0 4 0 92 1 2| 0 0 :1320k 2676k:1608k 2548k: 968k
2572k:3896k 7796k>
0 2 0 96 1 1| 0 0 :1856k 1808k:1752k 1988k:1752k
1600k:5360k 5396k>
0 4 0 92 2 1| 0 0 :1360k 2560k:1240k 2788k:1580k
2940k:4180k 8288k>
0 2 0 97 1 2| 0 0 :1928k 1456k:1628k 2080k:1488k
2308k:5044k 5844k>
1 3 0 94 2 2| 0 0 :1432k 2156k:1320k 1840k: 936k
1072k:3688k 5068k>
0 3 0 93 2 2| 0 0 :1760k 2164k:1440k 2384k:1276k
2972k:4476k 7520k>
0 3 0 95 1 2| 0 0 :1088k 1064k: 896k 1424k:1152k
992k:3136k 3480k>
0 0 0 96 0 2| 0 0 : 976k 888k: 632k 1120k:1016k
968k:2624k 2976k>
0 2 0 94 1 2| 0 0 :1120k 1864k: 964k 1776k:1060k
1856k:3144k 5496k>
--
Jon
prev parent reply other threads:[~2007-12-09 0:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-02 23:09 Reading takes 100% precedence over writes for mdadm+raid5? Justin Piszcz
2007-12-02 23:18 ` Neil Brown
2007-12-02 23:26 ` Justin Piszcz
2007-12-06 1:27 ` Jon Nelson
2007-12-06 9:06 ` Justin Piszcz
2007-12-06 9:26 ` David Rees
2007-12-06 9:27 ` Justin Piszcz
2007-12-06 13:43 ` Jon Nelson
2007-12-06 16:11 ` Bill Davidsen
2007-12-09 0:13 ` Jon Nelson [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=cccedfc60712081613t78451d3fm97ea782eef2be0ec@mail.gmail.com \
--to=jnelson@jamponi.net \
--cc=davidsen@tmr.com \
--cc=jpiszcz@lucidpixels.com \
--cc=linux-raid@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).