On Mon, Nov 16, 2015 at 6:05 AM, Jan Kara [off-list ref] wrote:

On Mon 16-11-15 14:37:14, Jan Kara wrote:

[..]

But a question: Won't it be better to do sfence + pcommit only in response
to REQ_FLUSH request and don't do it after each write? I'm not sure how
expensive these instructions are but in theory it could be a performance
win, couldn't it? For filesystems this is enough wrt persistency
guarantees...

We would need to gather the performance data...  The expectation is
that the cache flushing is more expensive than the sfence + pcommit.

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