From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Woodhouse Subject: [PATCH 9/7] blktrace: simplify flags handling in __blk_add_trace Date: Sun, 10 Aug 2008 12:48:22 +0100 Message-ID: <1218368902.5063.48.camel@pmac.infradead.org> References: <1218299181.26926.88.camel@pmac.infradead.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Andrew Morton , Ric Wheeler , linux-fsdevel@vger.kernel.org, gilad@codefidence.com, matthew@wil.cx To: Jens Axboe Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:35002 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752906AbYHJLss (ORCPT ); Sun, 10 Aug 2008 07:48:48 -0400 In-Reply-To: <1218299181.26926.88.camel@pmac.infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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 --- block/blktrace.c | 38 ++++++++------------------------------ 1 files changed, 8 insertions(+), 30 deletions(-) diff --git a/block/blktrace.c b/block/blktrace.c index 7495a84..9e0212c 100644 --- a/block/blktrace.c +++ b/block/blktrace.c @@ -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))) -- 1.5.5.1 -- David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation