From: Wen Yang <wenyang@linux.alibaba.com>
To: Andrew Morton <akpm@linux-foundation.org>, Qian Cai <cai@lca.pw>
Cc: xlpang@linux.alibaba.com, Wen Yang <wenyang@linux.alibaba.com>,
Tejun Heo <tj@kernel.org>, Jens Axboe <axboe@kernel.dk>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH 3/3] mm/page-writeback.c: improve arithmetic divisions
Date: Thu, 2 Jan 2020 16:14:42 +0800 [thread overview]
Message-ID: <20200102081442.8273-4-wenyang@linux.alibaba.com> (raw)
In-Reply-To: <20200102081442.8273-1-wenyang@linux.alibaba.com>
Use div64_ul() instead of do_div() if the divisor is unsigned long,
to avoid truncation to 32-bit on 64-bit platforms.
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/page-writeback.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index c74c6bd..2caf780 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1102,7 +1102,7 @@ static void wb_update_write_bandwidth(struct bdi_writeback *wb,
bw = written - min(written, wb->written_stamp);
bw *= HZ;
if (unlikely(elapsed > period)) {
- do_div(bw, elapsed);
+ bw = div64_ul(bw, elapsed);
avg = bw;
goto out;
}
--
1.8.3.1
prev parent reply other threads:[~2020-01-02 8:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-02 8:14 [PATCH 0/3] use div64_ul() instead of div_u64() if the divisor is unsigned long Wen Yang
2020-01-02 8:14 ` [PATCH 1/3] mm/page-writeback.c: avoid potential division by zero in wb_min_max_ratio() Wen Yang
2020-01-02 8:14 ` [PATCH 2/3] mm/page-writeback.c: use div64_ul() for u64-by-unsigned-long divide Wen Yang
2020-01-02 8:14 ` Wen Yang [this message]
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