On Fri, Oct 19, 2012 at 11:00 PM, Amit kapila <amit.kapila@huawei.com> wrote:
>
>> Robert wrote an accounting patch a while ago that tallied how often a
>> buffer was cleaned but then reclaimed for the same page before being
>> evicted. But now I can't find it. If you can find that thread, there
>> might be some benchmarks posted to it that would be useful.
>
> In my first level search, I am also not able to find it. But now I am planning to check all
> mails of Robert Haas on PostgreSQL site (which are approximately 13,000).
> If you can tell me how long ago approximately (last year, 2 yrs back, ..) or whether such a patch is submitted
> to any CF or was just discussed in mail chain, then it will be little easier for me.
It was just an instrumentation patch for doing experiments, not
intended for commit.
I've tracked it down to the thread "Initial 9.2 pgbench write
results". But I don't think it applies to the -S benchmark, because
it records when the background writer cleaned a buffer by finding it
dirty and writing it out to make it clean, while in this situation we
would need something more like "either made the buffer clean and
reusable, observed the buffer to already be clean and reusable"
Cheers,
Jeff