xfs: mark the xfssyncd workqueue as non-reentrant
PATCH 1/1 xfs: mark the xfssyncd workqueue as non-reentrant
On a system with lots of memory pressure that is stuck on synchronous inode reclaim the workqueue code will run one instance of the inode reclaim work item on every CPU. which is not what we want. Make sure to mark the xfssyncd workqueue as non-reentrant to make sure there only is one instace of each running globally. Also stop using special paramater for the workqueue; now that we guarantee each fs has only running one of each works at a time there is no need to artificially lower max_active and compensate for that by setting the WQ_CPU_INTENSIVE flag.
fs/xfs/xfs_super.c +5 -5
@@ -1641,12 +1641,12 @@ STATIC int __initxfs_init_workqueues (void) {/* -* max_active is set to 8 to give enough concurency to allow -* multiple work operations on each CPU to run. This allows multiple -* filesystems to be running sync work concurrently, and scales with -* the number of CPUs in the system. +* We never want to the same work item to run twice, reclaiming inodes +* or idling the log is not going to get any faster by multiple CPUs +* competing for ressources. Use the default large max_active value +* so that even lots of filesystems can perform these task in parallel. */ - xfs_syncd_wq =alloc_workqueue ("xfssyncd" ,WQ_CPU_INTENSIVE ,8 ); + xfs_syncd_wq =alloc_workqueue ("xfssyncd" ,WQ_NON_REENTRANT ,0 );if (!xfs_syncd_wq)return -ENOMEM ;return 0 ;
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Quoted 10 lines · Christoph Hellwig
On a system with lots of memory pressure that is stuck on synchronous inode reclaim the workqueue code will run one instance of the inode reclaim work item on every CPU. which is not what we want. Make sure to mark the xfssyncd workqueue as non-reentrant to make sure there only is one instace of each running globally. Also stop using special paramater for the workqueue; now that we guarantee each fs has only running one of each works at a time there is no need to artificially lower
max_activeand compensate for that by setting theWQ_CPU_INTENSIVEflag.Signed-off-by Christoph Hellwig <[email protected]>
Ok, I've had a look in detail at what the WQ_NON_REENTRANT flag does and I agree that this is the correct behaviour for the xfssyncd - only one instance per filesystem should run at any given time.
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Ben Myers
Reviewed-byQuoted 10 lines · Dave Chinner
Quoted 9 lines · Christoph Hellwig
On a system with lots of memory pressure that is stuck on synchronous inode reclaim the workqueue code will run one instance of the inode reclaim work item on every CPU. which is not what we want. Make sure to mark the xfssyncd workqueue as non-reentrant to make sure there only is one instace of each running globally. Also stop using special paramater for the workqueue; now that we guarantee each fs has only running one of each works at a time there is no need to artificially lower
max_activeand compensate for that by setting theWQ_CPU_INTENSIVEflag.
Quoted 7 lines
Quoted 1 line
Signed-off-by Christoph Hellwig <[email protected]>Ok, I've had a look in detail at what the
WQ_NON_REENTRANTflag does and I agree that this is the correct behaviour for the xfssyncd - only one instance per filesystem should run at any given time.Reviewed-by Dave Chinner <[email protected]>
FWICS this seems reasonable...
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