From: Martin Svec Date: Tue, 15 Jan 2013 20:43:35 +0000 (-0800) Subject: target/rd: improve sg_table lookup scalability X-Git-Tag: v3.9-rc1~71^2~22 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8f67835f1e389978bb0809d5e528961986aa2a69;p=pandora-kernel.git target/rd: improve sg_table lookup scalability Sequential scan of rd_dev->sg_table_array in rd_get_sg_table is a serious I/O performance bottleneck for large rd LUNs. Fix this by computing the sg_table index directly from page offset because all sg_tables (except the last one) have the same number of pages. Tested with 90 GiB rd_mcp LUN, where the patch improved maximal random R/W IOPS by more than 100-150%, depending on actual hardware and SAN setup. Signed-off-by: Martin Svec Signed-off-by: Nicholas Bellinger --- Reading git-diff-tree failed