From: Yury Norov <yury.norov@gmail.com>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-mmc@vger.kernel.org
Cc: Yury Norov <yury.norov@gmail.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Tejun Heo <tj@kernel.org>, Steven Rostedt <rostedt@goodmis.org>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
Dennis Zhou <dennis@kernel.org>, Christoph Lameter <cl@linux.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 1/4] mm/percpu: micro-optimize pcpu_is_populated()
Date: Sun, 18 Jul 2021 19:17:52 -0700 [thread overview]
Message-ID: <20210719021755.883182-2-yury.norov@gmail.com> (raw)
In-Reply-To: <20210719021755.883182-1-yury.norov@gmail.com>
bitmap_next_clear_region() calls find_next_zero_bit() and find_next_bit()
sequentially to find a range of clear bits. In case of pcpu_is_populated()
there's a chance to return earlier if bitmap has all bits set.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
mm/percpu.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index 7f2e0151c4e2..25461571dcc5 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1071,17 +1071,18 @@ static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
int *next_off)
{
- unsigned int page_start, page_end, rs, re;
+ unsigned int start, end;
- page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
- page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
+ start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
+ end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
- rs = page_start;
- bitmap_next_clear_region(chunk->populated, &rs, &re, page_end);
- if (rs >= page_end)
+ start = find_next_zero_bit(chunk->populated, end, start);
+ if (start >= end)
return true;
- *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
+ end = find_next_bit(chunk->populated, end, start + 1);
+
+ *next_off = end * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
return false;
}
--
2.30.2
next prev parent reply other threads:[~2021-07-19 2:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 2:17 [PATCH v2 0/4] bitmap: unify for_each_bit() macros Yury Norov
2021-07-19 2:17 ` Yury Norov [this message]
2021-07-21 21:07 ` [PATCH 1/4] mm/percpu: micro-optimize pcpu_is_populated() Dennis Zhou
2021-07-19 2:17 ` [PATCH 2/4] bitmap: unify find_bit operations Yury Norov
2021-07-21 21:12 ` Dennis Zhou
2021-08-04 10:07 ` Ulf Hansson
2021-08-11 7:38 ` Wolfram Sang
2021-08-12 1:23 ` Yury Norov
2021-07-19 2:17 ` [PATCH 3/4] lib: bitmap: add performance test for bitmap_print_to_pagebuf Yury Norov
2021-07-19 2:17 ` [PATCH 4/4] vsprintf: rework bitmap_list_string Yury Norov
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