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Increase arc_c_min to allow safe operation of arc_adapt()

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ZoL had lowered the minimum ARC size to 4MiB to better accommodate tiny
systems such as the raspberry pi, however, as of addition of large block
support, the arc_adapt() function depends on arc_c being >= 32MiB (2 *
SPA_MAXBLOCKSIZE).

This patch raises the minimum ARC size to 32MiB and adds a VERIFY test
to arc_adapt() for future-proofing.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Tim Chase 2015-06-04 08:06:27 -05:00 committed by Brian Behlendorf
parent f604673836
commit 121b3cae74
1 changed files with 8 additions and 6 deletions
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14
module/zfs/arc.c
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@ -3088,8 +3088,8 @@ arc_adapt_thread(void)
zfs_arc_max != arc_c_max)
arc_c_max = zfs_arc_max;
if (zfs_arc_min > 0 &&
zfs_arc_min < arc_c_max &&
if (zfs_arc_min >= 2ULL << SPA_MAXBLOCKSHIFT &&
zfs_arc_min <= arc_c_max &&
zfs_arc_min != arc_c_min)
arc_c_min = zfs_arc_min;
@ -3355,7 +3355,8 @@ arc_adapt(int bytes, arc_state_t *state)
* If we're within (2 * maxblocksize) bytes of the target
* cache size, increment the target cache size
*/
if (arc_size > arc_c - (2ULL << SPA_MAXBLOCKSHIFT)) {
VERIFY3U(arc_c, >=, 2ULL << SPA_MAXBLOCKSHIFT);
if (arc_size >= arc_c - (2ULL << SPA_MAXBLOCKSHIFT)) {
atomic_add_64(&arc_c, (int64_t)bytes);
if (arc_c > arc_c_max)
arc_c = arc_c_max;
@ -4826,8 +4827,8 @@ arc_init(void)
spl_register_shrinker(&arc_shrinker);
#endif
/* set min cache to zero */
arc_c_min = 4<<20;
/* set min cache to allow safe operation of arc_adapt() */
arc_c_min = 2ULL << SPA_MAXBLOCKSHIFT;
/* set max to 1/2 of all memory */
arc_c_max = arc_c * 4;
@ -4837,7 +4838,8 @@ arc_init(void)
*/
if (zfs_arc_max > 64<<20 && zfs_arc_max < physmem * PAGESIZE)
arc_c_max = zfs_arc_max;
if (zfs_arc_min > 0 && zfs_arc_min <= arc_c_max)
if (zfs_arc_min >= 2ULL << SPA_MAXBLOCKSHIFT &&
zfs_arc_min <= arc_c_max)
arc_c_min = zfs_arc_min;
arc_c = arc_c_max;