Re: Change BgWriterCommLock to spinlock - Mailing list pgsql-patches

From Tom Lane
Subject Re: Change BgWriterCommLock to spinlock
Date
Msg-id 24000.1136762542@sss.pgh.pa.us
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In response to Re: Change BgWriterCommLock to spinlock  (Qingqing Zhou <zhouqq@cs.toronto.edu>)
Responses Re: Change BgWriterCommLock to spinlock
List pgsql-patches
Qingqing Zhou <zhouqq@cs.toronto.edu> writes:
> On Sun, 8 Jan 2006, Tom Lane wrote:
>> Why is this a good idea?

> "In spirit of incremental improvement":
> (1) The spinlock itself are light weight than the LWLock here and we can
> reduce the lock contention a little bit in AbsorbFsyncRequests();

Spinlock-based coding is inherently much more fragile than LWLock-based
coding.  I'm against changing things in that direction unless a
substantial performance improvement can be gained.  You didn't offer
any evidence of improvement at all.

> (2) Don't need the CRITICAL SECTION in AbsorbFsyncRequests() any more;

Really?  I think this coding still breaks, rather badly, if
RememberFsyncRequest fails.  Certainly the reasons for needing a
critical section have nothing to do with what kind of lock is used.

            regards, tom lane

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