xen-blkfront: Introduce a 'max' module parameter to alter the amount of indirect segments. (2d5dc3ba) · Commits · 戴 / test

The max module parameter (by default 32) is the maximum number of segments that the frontend will negotiate with the backend for indirect descriptors. Higher value means more potential throughput but more memory usage. The backend picks the minimum of the frontend and its default backend value. Signed-off-by:

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Documentation/ABI/testing/sysfs-driver-xen-blkfront

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Original line number	Diff line number	Diff line
		What: /sys/module/xen_blkfront/parameters/max
		Date: June 2013
		KernelVersion: 3.11
		Contact: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
		Description:
		Maximum number of segments that the frontend will negotiate
		with the backend for indirect descriptors. The default value
		is 32 - higher value means more potential throughput but more
		memory usage. The backend picks the minimum of the frontend
		and its default backend value.

drivers/block/xen-blkfront.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -95,6 +95,8 @@ static const struct block_device_operations xlvbd_block_fops;
		*/

		static unsigned int xen_blkif_max_segments = 32;
		module_param_named(max, xen_blkif_max_segments, int, S_IRUGO);
		MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)");

		#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)

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