Subject: Re: cloning the kernel - why long time in "Resolving 313037 deltas"

From: Andy Whitcroft <[email-masked]>
Date: Tue, 19 Dec 2006 10:24:29 +0000

Junio C Hamano wrote:
> Johannes Schindelin <[email-masked]> writes:
> 
>> Hi,
>>
>> in a very unscientific test, without your patch local cloning of the 
>> LilyPond repo takes 1m33s (user), and with your patch (pread() instead of 
>> mmap()) it takes 1m13s (user). The real times are somewhat bogus, but 
>> still in favour of pread(), but only by 8 seconds instead of 20.
>>
>> This is on Linux 2.4.32.
> 
> Interesting.  Anybody have numbers from 2.6?

On my debian etch system:

Linux version 2.6.17-2-686 (Debian 2.6.17-9) ([email-masked]) (gcc 
version 4.1.2 20060901 (prerelease) (Debian 4.1.1-13)) #1 SMP Wed Sep 13 
16:34:10 UTC 2006

I did one run first (not included) to get things nice and warm, then 
three runs of each.  Overall the same as reported elsewhere marginally 
better with pread().  I guess you could say a 20-30% improvement in 
system time which isn't to be sniffed at.

-apw

mmap():

real    1m5.187s
user    1m0.844s
sys     0m2.900s

real    1m6.748s
user    1m0.868s
sys     0m3.064s

real    1m5.604s
user    1m0.760s
sys     0m3.124s

pread():

real    1m4.676s
user    1m0.168s
sys     0m2.340s

real    1m3.563s
user    0m59.796s
sys     0m2.248s

real    1m4.066s
user    1m0.156s
sys     0m2.304s