From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 In-Reply-To: References: <542179FA.5040106@gmail.com> <54228237.5000805@gmail.com> Date: Wed, 24 Sep 2014 22:22:04 +0100 Message-ID: Subject: Re: [Question] How to perform stride access? From: Sitsofe Wheeler Content-Type: text/plain; charset=UTF-8 To: Jens Axboe Cc: Akira Hayakawa , andrey.v.kuzmin@gmail.com, "fio@vger.kernel.org" List-ID: (Adding Jens to the CC list) On 24 September 2014 10:52, Sitsofe Wheeler wrote: > On 24 September 2014 09:35, Akira Hayakawa wrote: >> >> However, I [...] think I still have a problem. >> >> I modified the command >> >> From: >>>> fio --name=test --filename=#{dev.path} --rw=write --ioengine=libaio --direct=1 --io_limit=32M --size=100% --ba=4k --bs=512 >> To: >> fio --name=test --filename=#{dev.path} --rw=write:4k --ioengine=libaio --direct=1 --io_limit=32M --bs=512 >> >> The result is the runtime is too short. > > This looks like a bug. I can reproduce it with 2.1.11-11-gb7f5 too: > > dd if=/dev/zero of=/dev/shm/1M bs=1M count=1 > fio --bs=4k --rw=write:4k --filename=/dev/shm/1M --stonewall --name=1M > --io_limit=1M --name=2M --io_limit=2M > [...] > > Run status group 0 (all jobs): > WRITE: io=512KB, aggrb=256000KB/s, minb=256000KB/s, maxb=256000KB/s, > mint=2msec, maxt=2msec > > Run status group 1 (all jobs): > WRITE: io=512KB, aggrb=256000KB/s, minb=256000KB/s, maxb=256000KB/s, > mint=2msec, maxt=2msec > > Why isn't io 1024KB for group 0? Additionally, shouldn't the total io > written each group be different? Jens? > >> I guess fio stops as soon as it reaches the end of the device. >> However, I want it to repeat over and over again until io_limit is fully consumed. >> >> Note that the device is smaller than 32M (it is only 508B). > > 508 bytes? But your block size is 512 bytes! Am I misunderstanding > what you're doing? > >> So, it should repeat more than 60 times. >> >> How can I repeat the workload? > > number_ios fails too and using zonesize/zoneskip also doesn't help. > The only thing left that springs to mind is to use loops or fix this > bug :-) > > >> Or, >> >> Building hand-made random map would suffice, I guess. > > I'm not sure I follow. The workload you gave above is sequential with > holes (--rw=write:4k) - why would we need a random map? -- Sitsofe | http://sucs.org/~sits/