Messages in this thread | | | Date | Fri, 25 May 2007 12:05:26 +0530 | From | "Nitin Gupta" <> | Subject | Re: [RFC] [-mm] Remove 'unsafe' LZO decompressor |
| |
Hi Markus,
On 5/25/07, Markus F.X.J. Oberhumer <markus@oberhumer.com> wrote: > Please do _not_ rewrite the LZO implementation just for coding style principles. > > The current miniLZO implementation is _extrememly_ well tested, pretty > optimized and quite portable. > > I agree that the implementation may look confusing, but you should be able to > make it look much better by removing all the unused #defines and #ifdef code > paths - LZO supports exotic things like 16-bit DOS and CRAY PVP memory models > which obviously are not needed in the kernel and account for quite a number of > abstractions (which are implemented through the preprocessor). > > Finally the current version has been tested with a lot of compilers and > contains accumulated knowledge about some hairy things - see > http://gcc.gnu.org/PR25196 for an example, as well as some not-yet identified > aliasing issue. > > ~Markus
I did not rewrite any part of your code except replacing COPY4() macro and some open-coded byte-by-byte copying with memcpy(). But this has resulted in very significant perf. loss (as suggested by results from Richard's tests) - so will rollback these changes.
Additionally following was done to _greatly_ reduce no. of LOC I had to retain. These should not affect code correctness and performance: - Used standard/kernel defined data types equivalent of lzo_* types. This resulted in removal of huge chunks of #ifdefs: lzo_byptep -> unsigned char * lzo_uint -> size_t lzo_xint -> size_t lzo_uintptr_t -> unsigned long lzo_uint32p -> uint32_t * - Removed everything #ifdefed under COPY_DICT -- from minilzo code I see that this is not #defined for LZO1X (safe/unsafe) (though I could not understand meaning behind COPY_DICT). - Removed everthing #ifdef'ed for LZO1Y, LZO1Z, other variants.
Thanks, Nitin - 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/
| |