Re: 8.0.X and the ARC patent

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: pgsql(at)mohawksoft(dot)com, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: 8.0.X and the ARC patent
Date: 2005-02-15 05:13:45
Message-ID: 8398.1108444425@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> And ARC has locking requirements that will make it very hard to fix our
> SMP buffer management problems in 8.1.

I am working on a buffer manager rewrite using the BufMgrLock breakup
and "clock sweep" management algorithm we've been discussing. At the
moment it's passing the regression tests but I'm sure there's some bugs
left :-(. I just now tried it on the infamous context-swap-storm test
case using a 4-way machine at Red Hat. PG 8.0 shows 20K or more CS/sec
and under 30% CPU usage in this situation. The patch shows 99% CPU
utilization and about 200 CS/sec (which is about nil, because the
machine shows ~100 CS/sec with nothing running except vmstat).

Still to be determined: what we lose in extra I/O from the presumably
less efficient cache management; also what sort of slowdown occurs on
a single-CPU machine that isn't going to get any benefit from the
increased amount of lock management. But it looks promising.

regards, tom lane

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2005-02-15 05:47:34 Re: Which release cycle are we in?
Previous Message Bruce Momjian 2005-02-15 04:59:15 I will be on Boston