Messages in this thread | | | Date | Tue, 15 May 2007 10:17:31 -0500 | From | Matt Mackall <> | Subject | Re: [rfc][patch] slob: improvements |
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On Tue, May 15, 2007 at 10:43:05AM +0200, Nick Piggin wrote: > This patch goes on top of my previous RCU patch, and has various > improvements for slob I noticed while implementing said patch ;) > > Comments?
I'm warming to this. Please check that the comment block at the top is still accurate.
> +/* > + * slob_block has a field 'units', which indicates size of block if +ve, > + * or offset of next block if -ve (in SLOB_UNITs). > + * > + * Free blocks of size 1 unit simply contain the offset of the next block. > + * Those with larger size contain their size in the first SLOB_UNIT of > + * memory, and the offset of the next free block in the second SLOB_UNIT. > + */ > +#if PAGE_SIZE <= (32*1024) > +typedef s16 slobidx_t; > +#else > +typedef s32 slobidx_t; > +#endif
This math is wrong because you're doing pointer math on slobidx_ts:
> +static slob_t *slob_next(slob_t *s) > +{ > + slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK); > + slobidx_t next; > + > + if (s[0].units < 0) > + next = -s[0].units; > + else > + next = s[1].units; > + return base+next; > +}
The max is 64K.
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