On Tue, May 27, 2014 at 08:26:53AM +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@xxxxxxxxxx> > > Upon memory pressure, kswapd calls xfs_vm_writepage() from > shrink_page_list(). This can result in delayed allocation occurring > and that gets deferred to the the allocation workqueue. > > The allocation then runs outside kswapd context, which means if it > needs memory (and it does to demand page metadata from disk) it can > block in shrink_inactive_list() waiting for IO congestion. These > blocking waits are normally avoiding in kswapd context, so under > memory pressure writeback from kswapd can be arbitrarily delayed by > memory reclaim. > > To avoid this, pass the kswapd context to the allocation being done > by the workqueue, so that memory reclaim understands correctly that > the work is being done for kswapd and therefore it is not blocked > and does not delay memory reclaim. > > To avoid issues with int->char conversion of flag fields (as noticed > in v1 of this patch) convert the flag fields in the struct > xfs_bmalloca to bool types. pahole indicates these variables are > still single byte variables, so no extra space is consumed by this > change. Looks good, Reviewed-by: Christoph Hellwig <hch@xxxxxx> _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
