lkml.org 
[lkml]   [2007]   [May]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] LZO de/compression support - take 6
On 5/28/07, Nitin Gupta <nitingupta910@gmail.com> wrote:
> Hi,
>
> This is kernel port of LZO1X-1 compressor and LZO1X decompressor (safe
> version only).
>
> * Changes since 'take 5' (Full Changelog after this):
> - Added compressor and decomrpesssor as separate and hidden config
> options (default: n)
> - Cleanups: removed LZO_CHECK_MPOS_NON_DET macro
> - removed PTR* macros.
>
> * Benchmarks: (system: P4 3GHz, 1G RAM)
> (Using tester program from Daniel)
>
> Following compares this kernel port ('take 6') vs original miniLZO code:
>
> 'TinyLZO' refers to this kernel port.
>
> 10000 run averages:
> 'Tiny LZO':
> Combined: 61.2223 usec
> Compression: 41.8412 usec
> Decompression: 19.3811 usec
> 'miniLZO':
> Combined: 66.0444 usec
> Compression: 46.6323 usec
> Decompression: 19.4121 usec
>
> Result:
> Overall: TinyLZO is 7.3% faster
> Compressor: TinyLZO is 10.2% faster
> Decompressor: TinyLZO is 0.15% faster
>
> TODO: test 'take 6' port on archs other than x86(_32)
>
> * Changelog vs. original LZO:
> 1) Used standard/kernel defined data types: (this eliminated _huge_
> #ifdef chunks)
> lzo_bytep -> unsigned char *
> lzo_uint -> size_t
> lzo_xint -> size_t
> lzo_uint32p -> u32 *
> lzo_uintptr_t -> unsigned long
> 2) Removed everything #ifdef'ed under COPY_DICT (this is not set for
> LZO1X, so removed corres. parts).
> 3) Removed code #ifdef'ed for LZO1Y, LZO1Z, other variants.
> 4) Reformatted the code to match general kernel style.
> 5) The only code change: (as suggested by Andrey)
> -#if defined(__LITTLE_ENDIAN)
> - m_pos = op - 1;
> - m_pos -= (*(const unsigned short *)ip) >> 2;
> -#else
> - m_pos = op - 1;
> - m_pos -= (ip[0] >> 2) + (ip[1] << 6);
> -#endif
>
> + m_pos = op - 1 - (cpu_to_le16(*(const u16 *)ip) >> 2);
>
> (Andrey suggested le16_to_cpu for above but I think it should be cpu_to_le16).
> *** Need testing on big endian machine ***
>
> Similarly:
> -#if defined(__LITTLE_ENDIAN)
> - m_pos -= (*(const unsigned short *)ip) >> 2;
> -#else
> - m_pos -= (ip[0] >> 2) + (ip[1] << 6);
> -#endif
>
> + m_pos -= cpu_to_le16(*(const u16 *)ip) >> 2;
>
> 6) Get rid of LZO_CHECK_MPOS_NON_DET macro and PTR* macros.
>
>
> I think it's now ready for mainline inclusion.
>
>
> include/linux/lzo1x.h | 66 +++++++++++
> lib/Kconfig | 6 +
> lib/Makefile | 2 +
> lib/lzo1x/Makefile | 2 +
> lib/lzo1x/lzo1x_compress.c | 259

tested this on ppc and its still good
is there any reason to bother with a test on amd64?
if there is I might be able to get to it tonight
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-05-29 00:57    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site