powerpc: Preload application text segment instead of TASK_UNMAPPED_BASE

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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

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

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Anton Blanchard 2009-07-13 20:53:53 +00:00 • committed by Benjamin Herrenschmidt

parent 5eb9bac040

commit de4376c284

1 changed files with 8 additions and 9 deletions

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arch/powerpc/mm/slb.c

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