From: David Woodhouse Date: Mon, 26 Mar 2012 00:03:42 +0000 (+0000) Subject: ppp: Don't stop and restart queue on every TX packet X-Git-Tag: v3.4-rc2~11^2~41 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e675f0cc9a872fd152edc0c77acfed19bf28b81e;p=pandora-kernel.git ppp: Don't stop and restart queue on every TX packet For every transmitted packet, ppp_start_xmit() will stop the netdev queue and then, if appropriate, restart it. This causes the TX softirq to run, entirely gratuitously. This is "only" a waste of CPU time in the normal case, but it's actively harmful when the PPP device is a TEQL slave — the wakeup will cause the offending device to receive the next TX packet from the TEQL queue, when it *should* have gone to the next slave in the list. We end up seeing large bursts of packets on just *one* slave device, rather than using the full available bandwidth over all slaves. This patch fixes the problem by *not* unconditionally stopping the queue in ppp_start_xmit(). It adds a return value from ppp_xmit_process() which indicates whether the queue should be stopped or not. It *doesn't* remove the call to netif_wake_queue() from ppp_xmit_process(), because other code paths (especially from ppp_output_wakeup()) need it there and it's messy to push it out to the other callers to do it based on the return value. So we leave it in place — it's a no-op in the case where the queue wasn't stopped, so it's harmless in the TX path. Signed-off-by: David Woodhouse Signed-off-by: David S. Miller --- Reading git-diff-tree failed