Re: postgres processes spending most of their time in the

["Jeffrey W. Baker" <jwbaker(at)acm(dot)org>]

On Fri, 28 Dec 2001, Tom Lane wrote:

> "Jeffrey W. Baker" <jwbaker(at)acm(dot)org> writes:
> > I have a moderately loaded postgres server running 7.2beta4 (i wanted to
> > try out the live vacuum) that turns out to spend the majority of its cpu
> > time in kernel land.  With only a handful of running processes, postgres
> > induces tens of thousands of context switches per second.  Practically the
> > only thing postgres does with all this CPU time is semop() in a tight
> > loop.
>
> It sounds like you have a build that's using SysV semaphores in place of
> test-and-set instructions.  That should not happen on x86 hardware,
> since we have assembly TAS code for x86.  Please look at your port
> header file (src/include/pg_config_os.h symlink) and
> src/include/storage/s_lock.h to figure out why it's misbuilt.

Well, it seems that one of __i386__ or __GNUC__ isn't set at compile time.
I'm using GCC on i386 so I don't see how that is possible.  It should be
safe for me to simply define these two things in pg_config.h, I suspect.

-jwb