From: Julian Phillips <julian@quantumfyre.co.uk>
Date: Fri, 14 Nov 2008 00:04:35 GMT
Subject: Re: hosting git on a nfs
Message-ID: <alpine.LNX.2.00.0811140001070.5938@reaper.quantumfyre.co.uk>
In-Reply-To: <alpine.LFD.2.00.0811131518070.3468@nehalem.linux-foundation.org>

On Thu, 13 Nov 2008, Linus Torvalds wrote:

> The good news is that I seem to actualluy see a bit of a win from this
> even on a disk, now that the kernel doesn't serialize things. So it may
> be worth it. So I have some hope that it actually helps on NFS too.
> The numbers for five runs (with clearing of the caches in between, of
> course) are:
>
> Before:
>
> 	0.01user 0.23system 0:10.87elapsed 2%CPU
> 	0.04user 0.19system 0:10.86elapsed 2%CPU
> 	0.03user 0.26system 0:10.82elapsed 2%CPU
> 	0.02user 0.27system 0:12.67elapsed 2%CPU
> 	0.01user 0.22system 0:10.86elapsed 2%CPU
>
> After:
>
> 	0.03user 0.26system 0:07.88elapsed 3%CPU
> 	0.02user 0.25system 0:07.63elapsed 3%CPU
> 	0.01user 0.26system 0:08.62elapsed 3%CPU
> 	0.01user 0.26system 0:07.27elapsed 3%CPU
> 	0.05user 0.28system 0:08.61elapsed 3%CPU
>
> so it really does seem like it has possibly given a 30% improvement in
> cold-cache performance even on a disk.

On an NFS kernel checkout I get the following elapsed times:

master:

0:02.78
0:02.70
0:02.43
0:02.28
0:02.71
0:02.80
0:02.60
0:02.06
0:02.00

master + new patch:

0:00.77
0:00.83
0:01.02
0:00.77
0:00.91
0:00.78
0:00.78
0:01.09
0:01.00

-- 
Julian

  ---
There are no accidents whatsoever in the universe.
 		-- Baba Ram Dass