On Sun, Oct 15, 2006 at 12:37:28PM +1000, Bruce Evans wrote: > On Sun, 15 Oct 2006, Rink Springer wrote: > > >On Sat, Oct 14, 2006 at 07:25:12AM +0000, Bruce Evans wrote: > >> Log: > >> Don't do null Setattr RPCs for VA_MARK_ATIME. When we added the > >>... > >> This is the smallest and easiest to fix of several bugs that have > >> increased the number of RPCs for kernel builds on nfs by more than > >> 100% since 2004-11-05. The real-time increase depends on network > >>... > > >The code in RELENG_6 looks as if it would benefit from this change as > >well. Do you have a MFC planned in the nearby future? > > Maybe after the larger performance bugs are fixed. See a thread in > freebsd-fs. > > It would also be good to reduce nfs RPCs generally and there seems to > be a lot more scope to do this for Access ones, at least by automatically > configuring cases when a large timeout is safe. > > -current and RELENG_6 still have a bogus default of 2 for nfs_access_cache > in /etc/defaults/rc.conf, and rc.conf(5) still confusingly claims that > setting this to a value of 2-10 seconds will substantially reduce > network traffic. In fact the default is 60 and smaller nonzero settings > substantially increase network traffic; a setting of 2 is normally > made by the rc system, and settings of 3-10 only reduce network traffic > not so substantially by moving back towards the system default. Settings > of 2-10 substantially increase network traffic relative to the system > default.
> ISTR a discussion of fixing this in rc.conf, but nothing seems to have been > committed. The setting is confusing in the kernel too: ---------------------------- revision 1.285 date: 2006/05/24 00:06:14; author: kris; state: Exp; lines: +1 -1 Increase the nfs access cache timeout from 2 to 60. The latter is a more appropriate value and is also the default set by the kernel. I could not find a justification of why rc.conf began overriding it back in 1998. This dramatically cuts NFS traffic on e.g. a busy system with NFS root. Reviewed by: mohans MFC After: 2 weeks ---------------------------- Kris
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