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Message-ID: <CAHQAjVFTVf91Pk9rJQfsAkiuP896cfK7t9Pt2_ZOiLNq0FxYbg@mail.gmail.com>
Date: Fri, 15 Jul 2011 19:12:32 -0700
From: ersatz splatt <ersatzsplatt@...il.com>
To: Roland Dreier <roland@...estorage.com>
Cc: Matthew Wilcox <matthew@....cx>, Jens Axboe <axboe@...nel.dk>,
"Jiang, Dave" <dave.jiang@...el.com>,
"Williams, Dan J" <dan.j.williams@...el.com>,
"Foong, Annie" <annie.foong@...el.com>,
"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Nadolski, Edmund" <edmund.nadolski@...el.com>,
"Skirvin, Jeffrey D" <jeffrey.d.skirvin@...el.com>
Subject: Re: rq_affinity doesn't seem to work?
With the quickest and easiest fix (the first suggestion from Jens
Axboe), I was able to get another 20%+ in IOPS. Thank you.
(Pardon the previous ugly wrap on the data. I'm not sure how to stop
that with my e-mail vendor)
Driving more IOPS on the same system looks like this for me:
CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle
all 2.85 0.00 31.37 12.05 0.00 14.84 0.00 0.00 38.90
0 2.44 0.00 0.00 0.00 0.00 4.39 0.00 0.00 93.17
1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00
2 1.51 0.00 23.12 70.85 0.00 4.52 0.00 0.00 0.00
3 5.05 0.00 51.01 19.70 0.00 24.24 0.00 0.00 0.00
4 5.47 0.00 62.19 1.00 0.00 31.34 0.00 0.00 0.00
5 4.00 0.00 50.00 22.50 0.00 23.50 0.00 0.00 0.00
6 0.00 0.00 0.00 0.00 0.00 0.47 0.00 0.00 99.53
7 0.00 0.00 0.22 0.00 0.00 0.00 0.00 0.00 99.78
8 4.48 0.00 53.23 16.92 0.00 25.37 0.00 0.00 0.00
9 4.48 0.00 50.25 19.40 0.00 25.87 0.00 0.00 0.00
10 5.53 0.00 63.82 0.50 0.00 30.15 0.00 0.00 0.00
11 3.50 0.00 52.00 20.50 0.00 24.00 0.00 0.00 0.00
12 0.50 0.00 1.00 1.49 0.00 0.00 0.00 0.00 97.01
13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00
14 3.50 0.00 43.50 35.50 0.00 17.50 0.00 0.00 0.00
15 4.02 0.00 51.26 20.60 0.00 24.12 0.00 0.00 0.00
16 6.03 0.00 57.29 8.54 0.00 28.14 0.00 0.00 0.00
17 4.50 0.00 49.00 25.00 0.00 21.50 0.00 0.00 0.00
18 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00
19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00
20 4.98 0.00 57.21 11.44 0.00 26.37 0.00 0.00 0.00
21 4.50 0.00 54.00 16.00 0.00 25.50 0.00 0.00 0.00
22 5.50 0.00 58.00 7.00 0.00 29.50 0.00 0.00 0.00
23 4.00 0.00 49.50 22.50 0.00 24.00 0.00 0.00 0.00
I'm happy to have the performance improvement, but I would like to
know how I could do much better. The storage hardware is all capable
of about twice the IOPS I'm getting now.
I see that "sys" is eating most of the CPU time at this point. What
do I need to fix? Is fio too heavy in implementation? ... or is this
a scsi midlayer bottleneck?
I would be happy to get advice on what I should do to better
illuminate the bottleneck.
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