On Thu, Mar 03, 2011 at 11:29:54AM -0800, Mingming Cao wrote:
> While running ext4 testing on multiple core, we found there are per
> cpu ext4-dio-unwritten threads processing conversion from unwritten
> extents to written for IOs completed from async direct IO patch.
> Per filesystem is enough, we don't need per cpu threads to work on
> conversion.
>
> Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
Eric, would you be able to do a very quick sanity check on your
48-core machine? I can definitely see how having a huge number of
threads per file system could be problematic, especially on a system
with 32 or 64 ext4 file systems. I'm curious though if we'll end up
taking a performance hit on direct I/O workloads.
If I remember correctly we currently have large file create with DIO
turned off, right? Would it be possible to do a large file create
with DIO enabled, and do a quick run both with and without this patch?
In the future it would also be interesting to see how we are doing
versus other file systems using a DIO workload. This is a probably
another area where I suspect some lockstat and oprofile runs may give
us opportunities for further optimization.
- Ted
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