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[PATCH 58/60] staging: lustre: osc: avoid 64 divide in osc_cache_too_much

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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>
---
 drivers/staging/lustre/lustre/osc/osc_page.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/lustre/lustre/osc/osc_page.c b/drivers/staging/lustre/lustre/osc/osc_page.c
index 0461408..ab9d0d7 100644
--- a/drivers/staging/lustre/lustre/osc/osc_page.c
+++ b/drivers/staging/lustre/lustre/osc/osc_page.c
@@ -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;
-- 
1.8.3.1

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[PATCH 00/60] staging: lustre: batches of fixes for lustre client James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 21/60] staging: lustre: ptlrpc: correct use of list_add_tail() James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 11/60] staging: lustre: obd: RCU stalls in lu_cache_shrink_count() James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 12/60] staging: lustre: lmv: Error not handled for lmv_find_target James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 28/60] staging: lustre: ldlm: ASSERTION(flock->blocking_export!=0) failed James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 34/60] staging: lustre: libcfs: default CPT matches NUMA topology James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 25/60] staging: lustre: llite: normal user can't set FS default stripe James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 07/60] staging: lustre: ptlrpc: set proper mbits for EINPROGRESS resend James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 19/60] staging: lustre: llite: handle inactive OSTs better in statfs James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 05/60] staging: lustre: llite: check request != NULL in ll_migrate James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
    Re: [PATCH 05/60] staging: lustre: llite: check request != NULL in  ll_migrate Dan Carpenter <dan.carpenter@oracle.com> - 2017-01-30 12:40 +0100
  [PATCH 03/60] staging: lustre: clio: add cl_page LRU shrinker James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 09/60] staging: lustre: lmv: Correctly generate target_obd James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 04/60] staging: lustre: mdc: quiet console message for known -EINTR James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 33/60] staging: lustre: libcfs: avoid stomping on module param cpu_pattern James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 31/60] staging: lustre: clio: sync write should update mtime James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 35/60] staging: lustre: lov: ld_target could be NULL James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 18/60] staging: lustre: ptlrpc: skip lock if export failed James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 27/60] staging: lustre: mgc: handle config_llog_data::cld_refcount properly James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 16/60] staging: lustre: llite: don't ignore layout for group lock request James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 36/60] staging: lustre: header: remove assert from interval_set() James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 13/60] staging: lustre: obdclass: health_check to report unhealthy upon LBUG James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
    Re: [PATCH 13/60] staging: lustre: obdclass: health_check to report  unhealthy upon LBUG Dan Carpenter <dan.carpenter@oracle.com> - 2017-01-30 13:50 +0100
  [PATCH 15/60] staging: lustre: hsm: stack overrun in hai_dump_data_field James Simmons <jsimmons@infradead.org> - 2017-01-29 01:20 +0100
  [PATCH 55/60] staging: lustre: obd: move s3 in lmd_parse to inner loop James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 42/60] staging: lustre: ptlrpc: allow blocking asts to be delayed James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 53/60] staging: lustre: ptlrpc: update replay cursor when close during replay James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 54/60] staging: lustre: fid: Change positional struct initializers to C99 James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 43/60] staging: lustre: obd: remove OBD_NOTIFY_CREATE James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 41/60] staging: lustre: osc: osc_match_base prototype differs from declaration James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 51/60] staging: lustre: ptlrpc: update MODULE_PARAM_DESC in ptlrpcd.c James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 50/60] staging: lustre: ptlrpc: remove unused pc->pc_env James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 49/60] staging: lustre: socklnd: remove socklnd_init_msg James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 52/60] staging: lustre: linkea: linkEA size limitation James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 45/60] staging: lustre: libcfs: Change positional struct initializers to C99 James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 39/60] staging: libcfs: remove integer types abstraction from libcfs James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 48/60] staging: lustre: ksocklnd: ignore timedout TX on closing connection James Simmons <jsimmons@infradead.org> - 2017-01-29 01:30 +0100
  [PATCH 58/60] staging: lustre: osc: avoid 64 divide in osc_cache_too_much James Simmons <jsimmons@infradead.org> - 2017-01-29 01:40 +0100
  [PATCH 57/60] staging: lustre: lmv: remove nlink check in lmv_revalidate_slaves James Simmons <jsimmons@infradead.org> - 2017-01-29 01:40 +0100
  [PATCH 60/60] staging: lustre: libcfs: fix minimum size check for libcfs ioctl James Simmons <jsimmons@infradead.org> - 2017-01-29 01:40 +0100
    Re: [PATCH 60/60] staging: lustre: libcfs: fix minimum size check  for libcfs ioctl Dan Carpenter <dan.carpenter@oracle.com> - 2017-01-30 12:00 +0100
    Re: [PATCH 60/60] staging: lustre: libcfs: fix minimum size check  for libcfs ioctl Dan Carpenter <dan.carpenter@oracle.com> - 2017-01-30 12:00 +0100
  [PATCH 56/60] staging: lustre: llite: don't invoke direct_IO for the EOF case James Simmons <jsimmons@infradead.org> - 2017-01-29 01:40 +0100
  [PATCH 01/60] staging: lustre: llite: Remove access of stripe in ll_setattr_raw James Simmons <jsimmons@infradead.org> - 2017-01-29 01:40 +0100
  [PATCH 59/60] staging: lustre: ptlrpc : remove userland usage from ptlrpc James Simmons <jsimmons@infradead.org> - 2017-01-29 01:40 +0100
  [PATCH 44/60] staging: lustre: libcfs: fix error messages James Simmons <jsimmons@infradead.org> - 2017-01-29 01:50 +0100
  [PATCH 38/60] staging: lustre: llite: Adding timed wait in ll_umount_begin James Simmons <jsimmons@infradead.org> - 2017-01-29 02:20 +0100
  [PATCH 46/60] staging: lustre: mdc: Make IT_OPEN take lookup bits lock James Simmons <jsimmons@infradead.org> - 2017-01-29 02:50 +0100
  [PATCH 47/60] staging: lustre: mdc: avoid returning freed request James Simmons <jsimmons@infradead.org> - 2017-01-29 02:50 +0100
  [PATCH 40/60] staging: ptlrpc: leaked rs on difficult reply James Simmons <jsimmons@infradead.org> - 2017-01-29 06:00 +0100

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