linux-ext4 - Re: [PATCH] ext4: Use single thread to perform DIO unwritten convertion

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 5 Mar 2011 12:46:39 -0500
From:	Ted Ts'o <tytso@....edu>
To:	Eric Whitney <eric.whitney@...com>, Mingming Cao <cmm@...ibm.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: Use single thread to perform DIO unwritten
 convertion

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@...ibm.com>

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
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html