Re: limiting hint bit I/O
Cédric Villemain <cedric.villemain.debian@gmail.com>
From: Cédric Villemain <cedric.villemain.debian@gmail.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Merlin Moncure <mmoncure@gmail.com>, Jim Nasby <jim@nasby.net>, Kevin Grittner <Kevin.Grittner@wicourts.gov>, Josh Berkus <josh@agliodbs.com>, pgsql-hackers Hackers <pgsql-hackers@postgresql.org>
Date: 2011-02-05T22:04:48Z
Lists: pgsql-hackers
2011/2/5 Bruce Momjian <bruce@momjian.us>: > Robert Haas wrote: >> On Sat, Feb 5, 2011 at 10:37 AM, C?dric Villemain >> <cedric.villemain.debian@gmail.com> wrote: >> > Please update the commitfest with the accurate patch, there is only >> > the old immature v1 of the patch in it. >> > I was about reviewing it... >> > >> > https://commitfest.postgresql.org/action/patch_view?id=500 >> >> Woops, sorry about that. Here's an updated version, which I will also >> add to the CommitFest application. >> >> The need for this patch has been somewhat ameliorated by the fsync >> queue compaction patch. I tested with: > > Uh, in this C comment: > > + * or not we want to take the time to write it. We allow up to 5% of > + * otherwise-not-dirty pages to be written due to hint bit changes, > > 5% of what? 5% of all buffers? 5% of all hint-bit-dirty ones? Can you > clarify this in the patch? > The patch currently allow 100 buffers to be written consecutively each 2000 BufferAlloc. mmmhhh Robert, I am unsure with the hint_bit_write_allowance counter. It looks a bit fragile because nothing prevent hint_bit_write_allowance counter to increase a lot, so that is not 100 but X*100 next hint bit will be written. Isn't it ? Also, won't buffer_allocation_count hit INT limit ? -- Cédric Villemain 2ndQuadrant http://2ndQuadrant.fr/ PostgreSQL : Expertise, Formation et Support