cvs commit: src/sys/nfsclient nfs_vnops.c

[Rink Springer]

Hi Bruce,

On Sat, Oct 14, 2006 at 07:25:12AM +0000, Bruce Evans wrote:
> bde         2006-10-14 07:25:12 UTC
> 
>   FreeBSD src repository
> 
>   Modified files:
>     sys/nfsclient        nfs_vnops.c 
>   Log:
>   Don't do null Setattr RPCs for VA_MARK_ATIME.  When we added the
>   VA_MARK_ATIME feature to fix POSIX conformance fore execve() and mmap(),
>   we thought that it was optimized well enough for the one file system
>   that supports it (ffs) and harmless for other file systems (except
>   layered ones which already get the layering for VOP_SETATTR() wrong).
>   However, nfs_setattr() doesn't do much parameter checking, so when
>   it gets a combination of parameters that it doesn't understand, it
>   always does a Setattr RPC.  This RPC can't do anything good, and for
>   VA_MARK_ATIME it is null except for wasting a lot of time.
>   
>   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
>   latency and parallelization and can also be very large (approaching
>   the same percentage for unparallelized operations like "make depend"
>   on systems with fast CPUs and high-latency networks).
>   
>   Revision  Changes    Path
>   1.270     +2 -2      src/sys/nfsclient/nfs_vnops.c

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?

-- 
Rink P.W. Springer                                - http://rink.nu
"Patience is for those who cannot afford
 decent hardware."                                - Peter Koeleman
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