From owner-freebsd-smp Sat Nov 23 16:43:28 1996 Return-Path: owner-smp Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id QAA20651 for smp-outgoing; Sat, 23 Nov 1996 16:43:28 -0800 (PST) Received: from clem.systemsix.com (clem.systemsix.com [198.99.86.131]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id QAA20636 for ; Sat, 23 Nov 1996 16:43:19 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by clem.systemsix.com (8.6.12/8.6.12) with SMTP id RAA20563; Sat, 23 Nov 1996 17:43:09 -0700 Message-Id: <199611240043.RAA20563@clem.systemsix.com> X-Authentication-Warning: clem.systemsix.com: Host localhost didn't use HELO protocol X-Mailer: exmh version 1.6.5 12/11/95 From: Steve Passe To: dg@Root.COM cc: freebsd-smp@freefall.freebsd.org, Peter Wemm Subject: Re: SMP -current merge In-reply-to: Your message of "Sat, 23 Nov 1996 15:23:25 PST." <199611232323.PAA02050@root.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sat, 23 Nov 1996 17:43:09 -0700 Sender: owner-smp@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk Hi, I have tested the times reported by "time make" against a stopwatch, and they are accurate to within 0.5 second. I was surprised to see increasingly better times beyond "-j 2". I guess this is from parallelism on the disk accesses, ie when both CPUs are waiting for disk IO on a particular object build, there is another they can work on if jobs > 2. The point of diminishing returns seems to be around 8 jobs. ------------------------------ Summary of kernel build times: --- 1 CPU active, non SMP kernel: # time make: 446.65s real 337.68s user 22.54s system --- 2 CPUs active, idlequeue search in smp_idleloop(): # time make: 597.45s real 373.91s user 147.68s system --- 2 CPUs active, NO idlequeue search in smp_idleloop(): # time make: 433.87s real 332.11s user 44.69s system # time make -j 2: 326.28s real 400.29s user 67.71s system # time make -j 3: 293.41s real 420.08s user 77.28s system # time make -j 4: 285.10s real 425.32s user 79.71s system # time make -j 5: 277.74s real 428.25s user 78.97s system # time make -j 6: 276.35s real 429.64s user 80.22s system # time make -j 7: 274.97s real 432.54s user 80.01s system # time make -j 8: 274.53s real 431.80s user 81.16s system # time make -j 9: 276.46s real 433.53s user 81.20s system -- Steve Passe | powered by smp@csn.net | FreeBSD -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.6.2 mQCNAzHe7tEAAAEEAM274wAEEdP+grIrV6UtBt54FB5ufifFRA5ujzflrvlF8aoE 04it5BsUPFi3jJLfvOQeydbegexspPXL6kUejYt2OeptHuroIVW5+y2M2naTwqtX WVGeBP6s2q/fPPAS+g+sNZCpVBTbuinKa/C4Q6HJ++M9AyzIq5EuvO0a8Rr9AAUR tBlTdGV2ZSBQYXNzZSA8c21wQGNzbi5uZXQ+ =ds99 -----END PGP PUBLIC KEY BLOCK-----