Re: Thousands of semops for every i/o

On Mon, 2003-06-09 at 23:08, Tom Lane wrote:
> "Jeffrey W. Baker" <jwbaker@acm.org> writes:
> > This is the strace of a process which is deleting rows from four tables,
> > inside a transaction, one row at a time.  There are a lot of semops for
> > every i/o.  There are about 30 connections to this database currently.
> > I thought deletes in a transaction just flew along in Pg, because they
> > simply wrote the deleted transaction ID on the record.  It used to work
> > fine in my previous locally-built 7.2 on Debian, but this is 7.2.2 on
> > SuSE Enterprise Server 8.2.
>
> The first thing that comes to mind is that the thing is using SysV
> semaphores as a substitute for spinlocks.  If this is on a hardware
> platform that is supposed to have TAS() support in s_lock.h or s_lock.c,
> then it's a configuration or build error.  If it's on some heretofore
> unknown platform, you need to write some TAS() code to get decent
> performance.

It looks like a simple change in s_lock.h from

#if defined(__i386__)

to

#if defined(__i386__) || defined(__x86_64__)

Will be necessary for this platform.

Thanks,
jwb