From: Jesper Dangaard Brouer Date: Thu, 26 Jun 2014 11:16:49 +0000 (+0200) Subject: pktgen: avoid expensive set_current_state() call in loop X-Git-Tag: omap-for-v3.17/fixes-against-rc2~149^2~246^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=baac167b706600ebe7158acaeb7c489ae9d0bb8b;p=pandora-kernel.git pktgen: avoid expensive set_current_state() call in loop Avoid calling set_current_state() inside the busy-loop in pktgen_thread_worker(). In case of pkt_dev->delay, then it is still used/enabled in pktgen_xmit() via the spin() call. The set_current_state(TASK_INTERRUPTIBLE) uses a xchg, which implicit is LOCK prefixed. I've measured the asm LOCK operation to take approx 8ns on this E5-2630 CPU. Performance increase corrolate with this measurement. Performance data with CLONE_SKB==100000, rx-usecs=30: (single CPU performance, ixgbe 10Gbit/s, E5-2630) * Prev: 5454050 pps --> 183.35ns (1/5454050*10^9) * Now: 5684009 pps --> 175.93ns (1/5684009*10^9) * Diff: +229959 pps --> -7.42ns Signed-off-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- Reading git-diff-tree failed