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Commit 35ba8f70 authored by David Woodhouse's avatar David Woodhouse Committed by Jens Axboe
Browse files

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: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 27b29e86

block/blktrace.c

+8 −30
Original line number Diff line number Diff line
@@ -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)))