nfs: remove congestion_end() (c4dc4bee) · Commits · 戴 / test

These patches aim to improve balance_dirty_pages() and directly address three issues: 1) inter device starvation 2) stacked device deadlocks 3) inter process starvation 1 and 2 are a direct result from removing the global dirty limit and using per device dirty limits. By giving each device its own dirty limit is will no longer starve another device, and the cyclic dependancy on the dirty limit is broken. In order to efficiently distribute the dirty limit across the independant devices a floating proportion is used, this will allocate a share of the total limit proportional to the device's recent activity. 3 is done by also scaling the dirty limit proportional to the current task's recent dirty rate. This patch: nfs: remove congestion_end(). It's redundant, clear_bdi_congested() already wakes the waiters. Signed-off-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/nfs/write.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -242,10 +242,8 @@ static void nfs_end_page_writeback(struct page *page)
		struct nfs_server *nfss = NFS_SERVER(inode);

		end_page_writeback(page);
		if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH) {
		if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
		clear_bdi_congested(&nfss->backing_dev_info, WRITE);
		congestion_end(WRITE);
		}
		}

		/*

include/linux/backing-dev.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -93,7 +93,6 @@ static inline int bdi_rw_congested(struct backing_dev_info *bdi)
		void clear_bdi_congested(struct backing_dev_info *bdi, int rw);
		void set_bdi_congested(struct backing_dev_info *bdi, int rw);
		long congestion_wait(int rw, long timeout);
		void congestion_end(int rw);

		#define bdi_cap_writeback_dirty(bdi) \
		(!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))

mm/backing-dev.c

+0 −13

Original line number	Diff line number	Diff line
		@@ -54,16 +54,3 @@ long congestion_wait(int rw, long timeout)
		return ret;
		}
		EXPORT_SYMBOL(congestion_wait);

		/**
		* congestion_end - wake up sleepers on a congested backing_dev_info
		* @rw: READ or WRITE
		*/
		void congestion_end(int rw)
		{
		wait_queue_head_t *wqh = &congestion_wqh[rw];

		if (waitqueue_active(wqh))
		wake_up(wqh);
		}
		EXPORT_SYMBOL(congestion_end);

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