| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Return of the Solaris vacuum polling problem -- anyone remember this? |
| Date: | 2010-08-18 21:02:49 |
| Message-ID: | 13390.1282165369@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> Most likely that's the libc implementation of the select()-based sleeps
>> for vacuum_cost_delay. I'm still suspicious that the writes are eating
>> more cost_delay points than you think.
> Tested that. It does look like if I increase vacuum_cost_limit to 10000
> and lower vacuum_cost_page_dirty to 10, it reads 5-7 pages and writes
> 2-3 before each pollsys. The math seems completely wrong on that,
> though -- it should be 50 and 30 pages, or similar.
I think there could be a lot of cost_delay points getting expended
without any effects visible at the level of strace. Maybe try fooling
with vacuum_cost_page_hit and vacuum_cost_page_miss, too.
regards, tom lane
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