Re: Performance issue in 2.5.32+

From: Andi Kleen (ak@muc.de)
Date: Sun Sep 08 2002 - 06:57:47 EST


James Morris <jmorris@intercode.com.au> writes:

> I've noticed a significant performance hit on my system since 2.5.32.
> lmbench shows major changes in context switching latencies for 2.5.32 and
> 2.5.33 (see below, and profiling results for lat_ctx after that). This is
> on a dual celeron system with a Gigabyte GA6BXD motherboard. I can
> provide more hardware and configuration details if required.

2.5.32 added the TLS changes, which do rewrite the GDT in context switch.
Does it go away when you comment out the call to load_TLS in
arch/i386/kernel/process.c:__switch_to() ? (change should be harmless
unless you use a development glibc which uses TLS)

-Andi
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