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Increase spl_kmem_alloc_warn limit 

In order to support ABD with large blocks the spl_kmem_alloc_warn
limit needs to be increased to 64K.

A 16M block requires that pointers be stored for 4096 4K-pages
on an x86_64 system.  Each of these pointers is 8 bytes requiring
an allocation of 8*4096=32,768 bytes.  The addition of a small
header to this structure pushes the allocation over the default
32K warning threshold.

In addition, fix a small bug where MAX was used instead of MIN
when setting the default.  This ensures a reasonable limit is
still set on systems with page sizes larger then 4K.

Reviewed-by: David Quigley <david.quigley@intel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #571
This commit is contained in:
Brian Behlendorf 2016-09-16 17:10:36 -07:00 committed by GitHub
parent 49fbac3ace
commit cb81c0c588
1 changed files with 2 additions and 2 deletions
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4
module/spl/spl-kmem.c
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@ -35,7 +35,7 @@
* rate limited warning will be printed to the console for any kmem_alloc()
* which exceeds a reasonable threshold.
*
* The default warning threshold is set to eight pages but capped at 32K to
* The default warning threshold is set to sixteen pages but capped at 64K to
* accommodate systems using large pages. This value was selected to be small
* enough to ensure the largest allocations are quickly noticed and fixed.
* But large enough to avoid logging any warnings when a allocation size is
@ -44,7 +44,7 @@
* allocations are quickly caught. These warnings may be disabled by setting
* the threshold to zero.
*/
unsigned int spl_kmem_alloc_warn = MAX(8 * PAGE_SIZE, 32 * 1024);
unsigned int spl_kmem_alloc_warn = MIN(16 * PAGE_SIZE, 64 * 1024);
module_param(spl_kmem_alloc_warn, uint, 0644);
MODULE_PARM_DESC(spl_kmem_alloc_warn,
"Warning threshold in bytes for a kmem_alloc()");