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[IA64] remove dead BIO_VMERGE_BOUNDARY definition 

The block layer dropped the virtual merge feature
(b8b3e16cfe). BIO_VMERGE_BOUNDARY
definition is meaningless now (For IA64, BIO_VMERGE_BOUNDARY has been
meaningless for a long time since IA64 disables the virtual merge
feature).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
FUJITA Tomonori 2008-10-24 14:41:09 +09:00 committed by Tony Luck
parent 6a2d26fd3f
commit d8d54b0252
1 changed files with 0 additions and 24 deletions
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24
arch/ia64/include/asm/io.h
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@ -434,28 +434,4 @@ extern void memset_io(volatile void __iomem *s, int c, long n);
# endif /* __KERNEL__ */
/*
* Enabling BIO_VMERGE_BOUNDARY forces us to turn off I/O MMU bypassing. It is said that
* BIO-level virtual merging can give up to 4% performance boost (not verified for ia64).
* On the other hand, we know that I/O MMU bypassing gives ~8% performance improvement on
* SPECweb-like workloads on zx1-based machines. Thus, for now we favor I/O MMU bypassing
* over BIO-level virtual merging.
*/
extern unsigned long ia64_max_iommu_merge_mask;
#if 1
#define BIO_VMERGE_BOUNDARY 0
#else
/*
* It makes no sense at all to have this BIO_VMERGE_BOUNDARY macro here. Should be
* replaced by dma_merge_mask() or something of that sort. Note: the only way
* BIO_VMERGE_BOUNDARY is used is to mask off bits. Effectively, our definition gets
* expanded into:
*
* addr & ((ia64_max_iommu_merge_mask + 1) - 1) == (addr & ia64_max_iommu_vmerge_mask)
*
* which is precisely what we want.
*/
#define BIO_VMERGE_BOUNDARY (ia64_max_iommu_merge_mask + 1)
#endif
#endif /* _ASM_IA64_IO_H */