performance/io-threads: Provide option to turn off least-priority

RCA:
In cases when self-heal is in progress, self-heal fops are starved
because of least-priority. This affects other fops with conflicting
inode, entry locks with self-heal.

Fix:
This patch provides configuring enable/disable of least-priority.

Additional changes:
Moved RCHECKSUM fop to low instead of least because it will still
affect the performance of other fops if RCHECKSUM is in LEAST
priority.

Tests:
Tested that the enabling/disabling of fops is working fine.
Tested that RCHECKSUM fop priority is assigned LOW when
least-priority is disabled.

BUG: 843704
Signed-off-by: Pranith Kumar K <pranithk@gluster.com>
Change-Id: I892f99d6d0a3e0ae6c0a280f82e2203af0c346f6
Reviewed-on: http://review.gluster.com/3751
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/xlators/performance/io-threads/src/io-threads.h b/xlators/performance/io-threads/src/io-threads.h
index 7fd6cfea46a..feac5ae73fe 100644
--- a/xlators/performance/io-threads/src/io-threads.h
+++ b/xlators/performance/io-threads/src/io-threads.h
@@ -70,6 +70,7 @@ struct iot_conf {
         int                  queue_sizes[IOT_PRI_MAX];
         int                  queue_size;
         pthread_attr_t       w_attr;
+        gf_boolean_t         least_priority; /*Enable/Disable least-priority */
 
         xlator_t            *this;
 };