Date: Sat, 30 Sep 2006 14:46:36 -0400 From: Kris Kennaway <kris@obsecurity.org> To: Michel Talon <talon@lpthe.jussieu.fr> Cc: ports@freebsd.org Subject: Re: Yet another INDEX builder. Message-ID: <20060930184636.GA76783@xor.obsecurity.org> In-Reply-To: <20060930134951.GA89865@lpthe.jussieu.fr> References: <20060930134951.GA89865@lpthe.jussieu.fr>
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--cWoXeonUoKmBZSoM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Sep 30, 2006 at 03:49:51PM +0200, Michel Talon wrote: > Kris Kennaway said: >=20 > > FYI, I'm not sure if the python version is parallelizable, but you do > > get a small benefit from using parallelized 'make index' builds (via > > INDEX_JOBS) on a typical SMP machine. >=20 > My script runs parallel makes, of the order of ten simultaneous makes. OK, FYI I see a performance drop if you use too much parallelism (10 is "far too much" on a typical system; ~3 is probably optimal for a HTT machine). > You can see them, running top at the same time, but of course they are ve= ry > transient, since usually one make lasts of the order of 0.1 s on my machi= ne. > Anyways, still on my machine i have gained of the order of 20% wall clock= time > by doing that. And it is only an hyperthreaded P4 (running in SMP mode). = This > is why i was curious to know the effect of this idea on a machine with re= al > SMP and perhaps disks supporting tagged queuing, which should allow better > throughput for these simultaneous makes. I had, perhaps naively, assumed = that > with a good machine one can divide time by 2. The only situation where you might reasonably expect to see something approaching a factor of 2 speed improvement is if your ports tree is on a striped or mirrored device on separate controllers, so 2 reads can be completely decoupled from each other in hardware. I've not tried this though. Kris --cWoXeonUoKmBZSoM Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFFHruMWry0BWjoQKURAuv/AKD0L+qcyOV1VTINQXolKXsvau56PQCglije WrNHv5UEtgCOQapobtg0imY= =gFHc -----END PGP SIGNATURE----- --cWoXeonUoKmBZSoM--
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