lkml.org 
[lkml]   [2009]   [Aug]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/3] block: add blk-iopoll, a NAPI like approach for block devices
On Fri, Aug 07 2009, Jens Axboe wrote:
> On Fri, Aug 07 2009, Jens Axboe wrote:
> > > I'm not NAK'ing... just inserting some relevant NAPI field experience,
> > > and hoping for some numbers that better measure the costs/benefits.
> >
> > Appreciate you looking over this, and I'll certainly be posting some
> > more numbers on this. It'll largely depend on both storage, controller,
> > and worload.
>
> Here's a quick set of numbers, beating with random reads on a drive.
> Average of three runs for each, stddev is very low so confidence in the
> numbers should be high.
>
> With iopoll=0 (disabled), stock:
>
> blocksize IOPS ints/sec usr sys
> ------------------------------------------------------
> 4k 48401 ~30500 3.36% 27.26%
>
> clat (usec): min=1052, max=21615, avg=10541.48, stdev=243.48
> clat (usec): min=1066, max=22040, avg=10543.69, stdev=242.05
> clat (usec): min=1057, max=23237, avg=10529.04, stdev=239.30
>
>
> With iopoll=1
>
> blocksize IOPS ints/sec usr sys
> ------------------------------------------------------
> 4k 48452 ~29000 3.37% 26.47%
>
>
> clat (usec): min=1178, max=21662, avg=10542.72, stdev=247.87
> clat (usec): min=1074, max=21783, avg=10534.14, stdev=240.54
> clat (usec): min=1102, max=22123, avg=10509.42, stdev=225.73

Lets raise the bar a bit, this time using 8k reads on the faster box.

iopoll=0

blocksize IOPS ints/sec usr sys
------------------------------------------------------
8k 64050 ~76000 4.12% 45.01%

clat (usec): min=1326, max=18994, avg=7967.54, stdev=214.12
clat (usec): min=1325, max=25404, avg=7968.06, stdev=239.87
clat (usec): min=1273, max=21414, avg=7963.43, stdev=231.27


iopoll=1

blocksize IOPS ints/sec usr sys
------------------------------------------------------
8k 64162 ~55000 4.07% 42.32%

clat (usec): min=1380, max=19681, avg=7960.31, stdev=197.41
clat (usec): min=1370, max=37508, avg=7954.61, stdev=210.35
clat (usec): min=1332, max=23383, avg=7947.99, stdev=209.60

Again, purely a synthetic IO benchmark, but the sys reduction is
interesting.


--
Jens Axboe



\
 
 \ /
  Last update: 2009-08-07 13:35    [W:0.103 / U:0.240 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site