Date: Tue, 23 Jan 2007 15:39:21 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Bruce Evans <bde@zeta.org.au> Cc: fs@freebsd.org Subject: Re: more lost dotdot caching pessimizes nfs especially Message-ID: <20070123133921.GL71333@deviant.kiev.zoral.com.ua> In-Reply-To: <20070123233124.R33734@delplex.bde.org> References: <20070123233124.R33734@delplex.bde.org>
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--00hq2S6J2Jlg6EbK Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jan 24, 2007 at 12:18:38AM +1100, Bruce Evans wrote: > I suspect that recent locking fixes near dotdot are responsible for > slowing down builds over nfs even further by increasing the number > of RPCs. Times and RPC counts for building a RELENG_4 kernel under > -current on a Turion X2 2GHz: >=20 > With i386 SMP kernel built a few days ago: > %%% > make depend: > 9.31 real 5.04 user 1.25 sys > Lookup Read Write Access Getattr Other Total > 1269 541 591 20633 447 112 23593 >=20 > make: > 67.28 real 55.55 user 3.86 sys > Lookup Read Write Create Access Fsstat Other Total > 4633 2370 5291 436 22269 1726 14 36739 > %%% >=20 > With i386 SMP kernel built an hour ago: > %%% > make depend: > 13.70 real 5.38 user 1.56 sys > Lookup Read Write Access Getattr Other Total > 14008 541 591 38615 447 96 54298 >=20 > make: > 71.49 real 55.21 user 4.45 sys > Lookup Read Write Create Access Fsstat Other Total > 19237 2370 5292 436 41860 1714 14 70923 > %%% >=20 > Note that only the number of Lookups and Access's changed significantly > (Access goes with Lookup). >=20 > This is without -j4 so that the slowdown is more obvious. "make depend" > is not parallelized, so -j4 has little effect for it, but -j4 now > speeds "make" up by even more than a factor of 2 by running more RPCs > in parallel. The speedup used to be only from 67.3 to 34.3 seconds, > but now it is from 71.5 to 34.8 seconds. >=20 > This is with my old fixes and hacks to reduce RPCs, and the network > tuned for latency (80 usec ping -f latency). Plain -current would use > about 120000 RPCs for "make" and thus take 10-20 seconds longer. It > would use a bit less than that for "make depend" and thus take 5-10 > seconds longer. "make depend" would take about twice as long as it > should. It can easily take much longer than that on machines with > larger network latency. >=20 Bruce, could you confirm that reversal of rev. 1.97 of vfs_lookup.c would restore the old Lookup/Access RPC statistic ? --00hq2S6J2Jlg6EbK Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQFFthAIC3+MBN1Mb4gRAoWUAJ4xsM5HPX5bb1X851EzriXU5x0esQCfRq/j PkM7zaWmF1JToNwfcvT02R0= =kyxA -----END PGP SIGNATURE----- --00hq2S6J2Jlg6EbK--
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