linux-kernel - Re: [RFC] LZO de/compression support

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Date:	Sat, 26 May 2007 21:17:22 +0200
From:	"roland" <devzero@....de>
To:	<nitingupta910@...il.com>
Cc:	<linux-kernel@...r.kernel.org>
Subject: Re: [RFC] LZO de/compression support - take 4

btw - does in-kernel lzo scale on SMP systems ?

is it a matter of lzo builtin compression or a matter of the component using 
in-kernel lzo compression ?

if i write/read data on reiser4 filesystem with lzo compression on - will 
all CPUs being used ?

just curious here, because i remember reading about a scale problem with zfs 
filesystem and gzip compression on solaris, so i'm just curious what to 
expect on linux.

regards
roland

ps:
btw - there is a smp aware lzop utility at lemley.net/lzop_patches/lzop.html




>Hi,
>
>This is kernel port of LZO1X compressor and LZO1X decompressor (safe
>version only).
>
>* Changes since 'take 3' (Full Changelog after this):
>1) Removed 'unsafe' decompressor - hence also do away with symlinks in
>Makefiles.
>2) Rolled back changes where I replaced COPY4 with memcpy() calls.
>This seemed to be causing too much perf. loss as shown by Richard's
>tests. Need perf. testing again to confirm that this patch has perf.
>comparable to original LZO code/Richard's patch.
>3) Some functions were inlined (DX2, DX3 etc.) - this also seemed to
>be one of factors for perf. loss. Changed them back Macros.
>4) Added back the 'register' keyword - again seemed to me one of
>factors for perf. loss.
>
>Once I pinpoint exact reason for bad perf., I will do above cleanups
>again. But this should not be reason for non-inclusion in mainline.
>These are only minor cleanups.
>
>Richard, can you please provide perf. results for this patch also?
>Also, can you please mail back latest version of your LZO patch? In
>meantime, I will try to include benchmarking support to the
>'compress-test' module. 

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