From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.126]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AC5B736AE5 for ; Mon, 9 Oct 2023 15:13:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="j4RDFyOe" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696864420; x=1728400420; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=dtFAZzUApLP9AYi7ZmvY2WLxR5mdEeY5EJ0egiuP32g=; b=j4RDFyOetpv3cAy1euoKlY56KeTtQ67SlUseiEN0ISfcdtJznmugVEzj wAG9DHrESpP3SFbOeWXLfeWdLwybvifjuqr6S1DcQKDIMVRuO/XKMcdHF kMA5hKo8Js2rmPtY/KiTuZllvnsrIYjEHTowvCK+nxx6urtpmGBVA9OMb 9TVcGqslhf30gDMTQFwOImmc9Jwgx9rIAnTnYzOaD2IyVGo3ccBMMJCLz wdN25HGN1yfwmMP1FEDuJeJr9iYayMCcefz+olsszfyRbtqu/GHFYxuZK 3m+QIZDOqYHX3TB2UmeCzFOkBfBSFfDiz1kK/bb6eS8H5x1xIfZXN970U Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10858"; a="369232286" X-IronPort-AV: E=Sophos;i="6.03,210,1694761200"; d="scan'208";a="369232286" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Oct 2023 08:13:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10858"; a="869288045" X-IronPort-AV: E=Sophos;i="6.03,210,1694761200"; d="scan'208";a="869288045" Received: from newjersey.igk.intel.com ([10.102.20.203]) by fmsmga002.fm.intel.com with ESMTP; 09 Oct 2023 08:13:29 -0700 From: Alexander Lobakin To: Yury Norov Cc: Alexander Lobakin , Andy Shevchenko , Rasmus Villemoes , Alexander Potapenko , Jakub Kicinski , Eric Dumazet , David Ahern , Przemek Kitszel , Simon Horman , netdev@vger.kernel.org, linux-btrfs@vger.kernel.org, dm-devel@redhat.com, ntfs3@lists.linux.dev, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 08/14] bitmap: introduce generic optimized bitmap_size() Date: Mon, 9 Oct 2023 17:10:20 +0200 Message-ID: <20231009151026.66145-9-aleksander.lobakin@intel.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231009151026.66145-1-aleksander.lobakin@intel.com> References: <20231009151026.66145-1-aleksander.lobakin@intel.com> Precedence: bulk X-Mailing-List: ntfs3@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The number of times yet another open coded `BITS_TO_LONGS(nbits) * sizeof(long)` can be spotted is huge. Some generic helper is long overdue. Add one, bitmap_size(), but with one detail. BITS_TO_LONGS() uses DIV_ROUND_UP(). The latter works well when both divident and divisor are compile-time constants or when the divisor is not a pow-of-2. When it is however, the compilers sometimes tend to generate suboptimal code (GCC 13): 48 83 c0 3f add $0x3f,%rax 48 c1 e8 06 shr $0x6,%rax 48 8d 14 c5 00 00 00 00 lea 0x0(,%rax,8),%rdx %BITS_PER_LONG is always a pow-2 (either 32 or 64), but GCC still does full division of `nbits + 63` by it and then multiplication by 8. Instead of BITS_TO_LONGS(), use ALIGN() and then divide by 8. GCC: 8d 50 3f lea 0x3f(%rax),%edx c1 ea 03 shr $0x3,%edx 81 e2 f8 ff ff 1f and $0x1ffffff8,%edx Now it divides `nbits + 63` by 8 and then masks bits[2:0]. bloat-o-meter: add/remove: 0/0 grow/shrink: 20/133 up/down: 156/-773 (-617) Clang does it better and generates the same code before/after starting from -O1, except that with the ALIGN() approach it uses %edx and thus still saves some bytes: add/remove: 0/0 grow/shrink: 9/133 up/down: 18/-538 (-520) Note that we can't expand DIV_ROUND_UP() by adding a check and using this approach there, as it's used in array declarations where expressions are not allowed. Add this helper to tools/ as well. Reviewed-by: Przemek Kitszel Signed-off-by: Alexander Lobakin --- drivers/md/dm-clone-metadata.c | 5 ----- include/linux/bitmap.h | 8 +++++--- include/linux/cpumask.h | 2 +- lib/math/prime_numbers.c | 2 -- tools/include/linux/bitmap.h | 8 +++++--- 5 files changed, 11 insertions(+), 14 deletions(-) diff --git a/drivers/md/dm-clone-metadata.c b/drivers/md/dm-clone-metadata.c index c43d55672bce..47c1fa7aad8b 100644 --- a/drivers/md/dm-clone-metadata.c +++ b/drivers/md/dm-clone-metadata.c @@ -465,11 +465,6 @@ static void __destroy_persistent_data_structures(struct dm_clone_metadata *cmd) /*---------------------------------------------------------------------------*/ -static size_t bitmap_size(unsigned long nr_bits) -{ - return BITS_TO_LONGS(nr_bits) * sizeof(long); -} - static int __dirty_map_init(struct dirty_map *dmap, unsigned long nr_words, unsigned long nr_regions) { diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 03644237e1ef..63e422f8ba3d 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -237,9 +237,11 @@ extern int bitmap_print_list_to_buf(char *buf, const unsigned long *maskp, #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1))) #define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1))) +#define bitmap_size(nbits) (ALIGN(nbits, BITS_PER_LONG) / BITS_PER_BYTE) + static inline void bitmap_zero(unsigned long *dst, unsigned int nbits) { - unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long); + unsigned int len = bitmap_size(nbits); if (small_const_nbits(nbits)) *dst = 0; @@ -249,7 +251,7 @@ static inline void bitmap_zero(unsigned long *dst, unsigned int nbits) static inline void bitmap_fill(unsigned long *dst, unsigned int nbits) { - unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long); + unsigned int len = bitmap_size(nbits); if (small_const_nbits(nbits)) *dst = ~0UL; @@ -260,7 +262,7 @@ static inline void bitmap_fill(unsigned long *dst, unsigned int nbits) static inline void bitmap_copy(unsigned long *dst, const unsigned long *src, unsigned int nbits) { - unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long); + unsigned int len = bitmap_size(nbits); if (small_const_nbits(nbits)) *dst = *src; diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index f10fb87d49db..dbdbf1451cad 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -821,7 +821,7 @@ static inline int cpulist_parse(const char *buf, struct cpumask *dstp) */ static inline unsigned int cpumask_size(void) { - return BITS_TO_LONGS(large_cpumask_bits) * sizeof(long); + return bitmap_size(large_cpumask_bits); } /* diff --git a/lib/math/prime_numbers.c b/lib/math/prime_numbers.c index d42cebf7407f..d3b64b10da1c 100644 --- a/lib/math/prime_numbers.c +++ b/lib/math/prime_numbers.c @@ -6,8 +6,6 @@ #include #include -#define bitmap_size(nbits) (BITS_TO_LONGS(nbits) * sizeof(unsigned long)) - struct primes { struct rcu_head rcu; unsigned long last, sz; diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h index f3566ea0f932..81a2299ace15 100644 --- a/tools/include/linux/bitmap.h +++ b/tools/include/linux/bitmap.h @@ -2,6 +2,7 @@ #ifndef _TOOLS_LINUX_BITMAP_H #define _TOOLS_LINUX_BITMAP_H +#include #include #include #include @@ -25,13 +26,14 @@ bool __bitmap_intersects(const unsigned long *bitmap1, #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1))) #define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1))) +#define bitmap_size(nbits) (ALIGN(nbits, BITS_PER_LONG) / BITS_PER_BYTE) + static inline void bitmap_zero(unsigned long *dst, unsigned int nbits) { if (small_const_nbits(nbits)) *dst = 0UL; else { - int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long); - memset(dst, 0, len); + memset(dst, 0, bitmap_size(nbits)); } } @@ -83,7 +85,7 @@ static inline void bitmap_or(unsigned long *dst, const unsigned long *src1, */ static inline unsigned long *bitmap_zalloc(int nbits) { - return calloc(1, BITS_TO_LONGS(nbits) * sizeof(unsigned long)); + return calloc(1, bitmap_size(nbits)); } /* -- 2.41.0