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staging: lustre: osc: avoid 64 divide in osc_cache_too_much 

The use of 64 bit time introduces an expensive 64 bit
division operation. Since the time lapse being calculated
in osc_cache_too_much will never be more than seventy years
we can cast the time lapse to an long and perform a normal
32 bit divison operation instead.

Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8835
Reviewed-on: https://review.whamcloud.com/23814
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
James Simmons 2017-01-28 19:05:26 -05:00 committed by Greg Kroah-Hartman
parent 1cf96da241
commit 86df59846c
1 changed files with 8 additions and 3 deletions
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11
drivers/staging/lustre/lustre/osc/osc_page.c
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@ -370,12 +370,17 @@ static int osc_cache_too_much(struct client_obd *cli)
return lru_shrink_min(cli);
} else {
time64_t duration = ktime_get_real_seconds();
long timediff;
/* knock out pages by duration of no IO activity */
duration -= cli->cl_lru_last_used;
duration >>= 6; /* approximately 1 minute */
if (duration > 0 &&
pages >= div64_s64((s64)budget, duration))
/*
* The difference shouldn't be more than 70 years
* so we can safely case to a long. Round to
* approximately 1 minute.
*/
timediff = (long)(duration >> 6);
if (timediff > 0 && pages >= budget / timediff)
return lru_shrink_min(cli);
}
return 0;