Re: Re: Red Hat to support PostgreSQL

On Thu, Jun 28, 2001 at 10:45:30AM -0400, Alex Pilosov wrote:
: On Wed, 27 Jun 2001, Philip Molter wrote:
:
: > On Wed, Jun 27, 2001 at 06:58:18PM -0400, Bruce Momjian wrote:
: > : My guess on this one is that Solaris is slower for PostgreSQL because
: > : process switching is _much_ heavier on Solaris than other OS's.  This is
: > : because of the way they implemented processes in SVr4.  They got quite
: > : heavy, almost requiring kernel threads so you weren't switching
: > : processes all the time.
: > :
: > : In a sense threads were a solution to a process bloating problem.
: > : Linux/BSD have much lighter processes and hence work better for
: > : PostgreSQL.  Again, this is only a guess.
: > :
: > : MySQL does more stuff with threads while PostgreSQL switches process
: > : because each backend is a process.
: >
: > Does more stuff with threads?  It does all stuff with threads.  Your
: > guess was our guess, which is why we tried shoving the thing over to a
: > Linux box.  Now if I only I could figure out why kernel CPU usage keeps
: > going up incrementally over time (went from roughly a 5% average to a
: > 16% average in two days) the more we run the system.  All signs are
: > pointing to postgres.
:
: Or Linux. Try 2.4 kernel which is far better as far as SMP goes.

We are running a 2.4 kernel.  All signs point to Postgres because it's
happening under both Linux and Solaris (although the effect is much
more pronounced under Solaris).

: Look at linux profiling tools.

I can profile all day long but when I see the same behavior under two
different operating systems caused by the same database, I naturally
gravitate towards the database being the problem, not the OS.

* Philip Molter
* DataFoundry.net
* http://www.datafoundry.net/
* philip@datafoundry.net