block: reorder request_queue to remove 64 bit alignment padding (d7b76301) · Commits · 戴 / test

Reorder request_queue to remove 16 bytes of alignment padding in 64 bit builds. On my config this shrinks the size of this structure from 1608 to 1592 bytes and therefore needs one fewer cachelines. Also trivially move the open bracket { to be on the same line as the structure name to make it easier to grep. Signed-off-by:

Richard Kennedy <richard@rsk.demon.co.uk> Acked-by:

Tejun Heo <tj@kernel.org> Signed-off-by:

Jens Axboe <jaxboe@fusionio.com>

include/linux/blkdev.h

+6 −7

Original line number	Diff line number	Diff line
		@@ -260,8 +260,7 @@ struct queue_limits {
		unsigned char discard_zeroes_data;
		};

		struct request_queue
		{
		struct request_queue {
		/*
		* Together with queue_head for cacheline sharing
		*/
		@@ -304,14 +303,14 @@ struct request_queue
		void *queuedata;

		/*
		* queue needs bounce pages for pages above this limit
		* various queue flags, see QUEUE_* below
		*/
		gfp_t bounce_gfp;
		unsigned long queue_flags;

		/*
		* various queue flags, see QUEUE_* below
		* queue needs bounce pages for pages above this limit
		*/
		unsigned long queue_flags;
		gfp_t bounce_gfp;

		/*
		* protects queue structures from reentrancy. ->__queue_lock should
		@@ -334,8 +333,8 @@ struct request_queue
		unsigned int nr_congestion_off;
		unsigned int nr_batching;

		void *dma_drain_buffer;
		unsigned int dma_drain_size;
		void *dma_drain_buffer;
		unsigned int dma_pad_mask;
		unsigned int dma_alignment;

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