From: willy@linux.intel.com (Matthew Wilcox)
Subject: [PATCH] Remove redundant writes to uncached sqe memory
Date: Sat, 10 May 2014 22:52:54 -0400 [thread overview]
Message-ID: <20140511025254.GC6121@linux.intel.com> (raw)
In-Reply-To: <536D3E3F.9050902@micron.com>
On Fri, May 09, 2014@01:44:47PM -0700, Sam Bradshaw wrote:
> The memset to clear the SQE in nvme_submit_iod() is made partially
> redundant by subsequent writes. This patch explicitly clears each
> SQE structure member in ascending order, eliminating the need for
> the memset. With this change, our perf runs show ~1.5% less time
> spent in the IO submission path and minor reduced q lock contention.
I'm shocked! I thought that zeroing the cacheline first would be better
performing than storing into parts of the cacheline. But I can't argue
with your numbers. I think your patch is missing a store to the metadata
element though; care to rerun your test with that added?
next prev parent reply other threads:[~2014-05-11 2:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-09 20:44 [PATCH] Remove redundant writes to uncached sqe memory Sam Bradshaw
2014-05-09 21:14 ` Matias Bjørling
2014-05-11 2:54 ` Matthew Wilcox
2014-05-11 2:52 ` Matthew Wilcox [this message]
2014-05-12 19:41 ` Sam Bradshaw (sbradshaw)
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