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Re: Poor thread performance on Linux vs. Solaris

On Tuesday 09 September 2003 11:16 am, you wrote:

> no need for HIGHPTE on 4GB boxes, in most cases. It's useful if the
> combined amount of pagetable allocation gets close to 1GB - which
> should clearly not be the case on your box.
> you might even opt for CONFIG_4G instead of CONFIG_64GB, if there's no
> RAM above 4GB physical. (check the bootup log's e820 map for the
> precise RAM layout.)

Thanks for the clarification.  I'll disable it.

> > Total count from the top of the oprofile results?
> yes.
> >  1392500
> 46827 in .text.lock.futex is 3% - assuming that there's only 10% idle
> time in the oprofile. This is not a catastrophic figure by itself.

A few things though:

1) I was starting and stopping the daemon by hand, so there's some idle 
slop before and after the performance test.

2) Something's fishy - every time I run oprofpp, the total count is always 
1392500.  If total count is a measure of the number of samples taken, 
that doesn't make sense - am I getting the count from the right place?  
Or is there some sort of bug in oprofile?  This is the first I've used 
the tool, so I could be using it incorrectly.

3) Here's an op_time from a few minutes ago, there's definitely 30% system 
time in the kernel:

2197       0.5577  0.0000 /e100
7900       2.0055  0.0000 /lib/libgcc_s-3.2.2-20030225.so.1
13846      3.5150  0.0000 /usr/lib/libstdc++.so.5.0.3
23459      5.9554  0.0000 /lib/tls/libpthread-0.34.so
98380     24.9751  0.0000 /lib/tls/libc-2.3.2.so
118517    30.0872  0.0000 /usr/src/linux-2.6.0-0.test4.1.32/vmlinux
126738    32.1742  0.0000 

There's clearly 30% system time in the kernel.  3% in .text.lock.futex 
doesn't make sense - where's the other 27%?



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