[Drbd-dev] [PATCH v4 01/11] block: make generic_make_request handle arbitrarily sized bios

[Ming Lin]

On Thu, Jun 4, 2015 at 5:06 PM, Mike Snitzer <snitzer at redhat.com> wrote:
> On Thu, Jun 04 2015 at  6:21pm -0400,
> Ming Lin <mlin at kernel.org> wrote:
>
>> On Thu, Jun 4, 2015 at 2:06 PM, Mike Snitzer <snitzer at redhat.com> wrote:
>> >
>> > We need to test on large HW raid setups like a Netapp filer (or even
>> > local SAS drives connected via some SAS controller).  Like a 8+2 drive
>> > RAID6 or 8+1 RAID5 setup.  Testing with MD raid on JBOD setups with 8
>> > devices is also useful.  It is larger RAID setups that will be more
>> > sensitive to IO sizes being properly aligned on RAID stripe and/or chunk
>> > size boundaries.
>>
>> I'll test it on large HW raid setup.
>>
>> Here is HW RAID5 setup with 19 278G HDDs on Dell R730xd(2sockets/48
>> logical cpus/264G mem).
>> http://minggr.net/pub/20150604/hw_raid5.jpg
>>
>> The stripe size is 64K.
>>
>> I'm going to test ext4/btrfs/xfs on it.
>> "bs" set to 1216k(64K * 19 = 1216k)
>> and run 48 jobs.
>
> Definitely an odd blocksize (though 1280K full stripe is pretty common
> for 10+2 HW RAID6 w/ 128K chunk size).

I can change it to 10 HDDs HW RAID6 w/ 128K chunk size, then use bs=1280K

>
>> [global]
>> ioengine=libaio
>> iodepth=64
>> direct=1
>> runtime=1800
>> time_based
>> group_reporting
>> numjobs=48
>> rw=read
>>
>> [job1]
>> bs=1216K
>> directory=/mnt
>> size=1G
>
> How does time_based relate to size=1G?  It'll rewrite the same 1 gig
> file repeatedly?

Above job file is for read.
For write, I think so.
Do is make sense for performance test?

>
>> Or do you have other suggestions of what tests I should run?
>
> You're welcome to run this job but I'll also check with others here to
> see what fio jobs we used in the recent past when assessing performance
> of the dm-crypt parallelization changes.

That's very helpful.

>
> Also, a lot of care needs to be taken to eliminate jitter in the system
> while the test is running.  We got a lot of good insight from Bart Van
> Assche on that and put it to practice.  I'll see if we can (re)summarize
> that too.

Very helpful too.

Thanks.

>
> Mike