Messages in this thread Patch in this message | | | From | George Spelvin <> | Date | Wed, 20 Mar 2019 23:07:46 -0400 | Subject | [RFC PATCH v1 29/50] fs/ocfs2/journal: Use prandom_u32() and not /dev/random for timeout |
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get_random_bytes() is expensive crypto-quality random numbers. If we're just doing random backoff, prandom_u32() is plenty.
(Not to mention fetching 8 bytes of seed material only to reduce it modulo 5000 is a huge waste.)
Also, convert timeouts to jiffies at compile time; convert milliseconds to jiffies before picking a random number in the range to take advantage of compile-time constant folding.
Signed-off-by: George Spelvin <lkml@sdf.org> Cc: Mark Fasheh <mark@fasheh.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: ocfs2-devel@oss.oracle.com --- fs/ocfs2/journal.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c index 68ba354cf3610..939a12e57fa8b 100644 --- a/fs/ocfs2/journal.c +++ b/fs/ocfs2/journal.c @@ -1884,11 +1884,8 @@ int ocfs2_mark_dead_nodes(struct ocfs2_super *osb) */ static inline unsigned long ocfs2_orphan_scan_timeout(void) { - unsigned long time; - - get_random_bytes(&time, sizeof(time)); - time = ORPHAN_SCAN_SCHEDULE_TIMEOUT + (time % 5000); - return msecs_to_jiffies(time); + return msecs_to_jiffies(ORPHAN_SCAN_SCHEDULE_TIMEOUT) + + prandom_u32_max(5 * HZ); } /* -- 2.26.0
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