Subject: Re: [patch 3/3] powerpc: Preload application text segment instead of TASK_UNMAPPED_BASE

From: Benjamin Herrenschmidt <[email-masked]>
Date: Tue, 14 Jul 2009 17:10:23 +1000

On Tue, 2009-07-14 at 16:53 +1000, Anton Blanchard wrote:
> plain text document attachment (preload_0x10000000)
> TASK_UNMAPPED_BASE is not used with the new top down mmap layout. We can
> reuse this preload slot by loading in the segment at 0x10000000, where almost
> all PowerPC binaries are linked at.
> 
> On a microbenchmark that bounces a token between two 64bit processes over pipes
> and calls gettimeofday each iteration (to access the VDSO), both the 32bit and
> 64bit context switch rate improves (tested on a 4GHz POWER6):
> 
> 32bit: 273k/sec -> 283k/sec
> 64bit: 277k/sec -> 284k/sec

Any chance you can put that little test program online somewhere ?

Cheers,
Ben.