Messages in this thread | | | Subject | Re: [RFC PATCH v1 29/50] fs/ocfs2/journal: Use prandom_u32() and not /dev/random for timeout | From | Joseph Qi <> | Date | Mon, 30 Mar 2020 20:09:33 +0800 |
| |
Sorry for the late reply since I might miss this mail.
On 2019/3/21 11:07, George Spelvin wrote: > 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);
Seems better include the prandom_u32_max() into msecs_to_jiffies()?
Thanks, Joseph > } > > /* >
| |