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blktrace: simplify flags handling in __blk_add_trace 

Let the compiler see what's going on, and it can all get a lot simpler.
On PPC64 this reduces the size of the code calculating these bits by
about 60%. On x86_64 it's less of a win -- only 40%.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
David Woodhouse 2008-08-10 12:33:00 +01:00 committed by Jens Axboe
parent 27b29e86bf
commit 35ba8f7083
1 changed files with 8 additions and 30 deletions
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38
block/blktrace.c
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@ -111,31 +111,9 @@ static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
*/
static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) };
/*
* Bio action bits of interest
*/
static u32 bio_act[17] __read_mostly = {
[1] = BLK_TC_ACT(BLK_TC_BARRIER),
[2] = BLK_TC_ACT(BLK_TC_SYNC),
[4] = BLK_TC_ACT(BLK_TC_AHEAD),
[8] = BLK_TC_ACT(BLK_TC_META),
[16] = BLK_TC_ACT(BLK_TC_DISCARD)
};
/*
* More could be added as needed, taking care to increment the decrementer
* to get correct indexing
*/
#define trace_barrier_bit(rw) \
(((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0))
#define trace_sync_bit(rw) \
(((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1))
#define trace_ahead_bit(rw) \
(((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD))
#define trace_meta_bit(rw) \
(((rw) & (1 << BIO_RW_META)) >> (BIO_RW_META - 3))
#define trace_discard_bit(rw) \
(((rw) & (1 << BIO_RW_DISCARD)) >> (BIO_RW_DISCARD - 4))
/* The ilog2() calls fall out because they're constant */
#define MASK_TC_BIT(rw, __name) ( (rw & (1 << BIO_RW_ ## __name)) << \
(ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - BIO_RW_ ## __name) )
/*
* The worker for the various blk_add_trace*() types. Fills out a
@ -155,11 +133,11 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
return;
what |= ddir_act[rw & WRITE];
what |= bio_act[trace_barrier_bit(rw)];
what |= bio_act[trace_sync_bit(rw)];
what |= bio_act[trace_ahead_bit(rw)];
what |= bio_act[trace_meta_bit(rw)];
what |= bio_act[trace_discard_bit(rw)];
what |= MASK_TC_BIT(rw, BARRIER);
what |= MASK_TC_BIT(rw, SYNC);
what |= MASK_TC_BIT(rw, AHEAD);
what |= MASK_TC_BIT(rw, META);
what |= MASK_TC_BIT(rw, DISCARD);
pid = tsk->pid;
if (unlikely(act_log_check(bt, what, sector, pid)))