On Mon, Mar 30, 2009 at 5:21 PM, Joakim Tjernlund <joakim.tjernl...@transmode.se> wrote: > pku....@gmail.com wrote on 30/03/2009 10:34:47: >> >> On Thu, Mar 26, 2009 at 1:51 AM, Joakim Tjernlund >> <joakim.tjernl...@transmode.se> wrote: >> > Anton Vorontsov <avoront...@ru.mvista.com> wrote on 25/03/2009 > 15:25:40: >> >> On Wed, Mar 25, 2009 at 02:30:49PM +0100, Joakim Tjernlund wrote: >> >> > >>From 1c2f23b1f37f4818c0fd0217b93eb38ab6564840 Mon Sep 17 00:00:00 >> > 2001 >> >> > From: Joakim Tjernlund <joakim.tjernl...@transmode.se> >> >> > Date: Tue, 24 Mar 2009 10:19:27 +0100 >> >> > Subject: [PATCH] ucc_geth: Move freeing of TX packets to NAPI > context. >> >> > Also increase NAPI weight somewhat. >> >> > This will make the system alot more responsive while >> >> > ping flooding the ucc_geth ethernet interaface. >> >> >> >> Some time ago I've tried a similar thing for this driver, but during >> >> tcp (or udp I don't quite remember) netperf tests I was getting tx >> >> watchdog timeouts after ~2-5 minutes of work. I was testing with a >> >> gigabit and 100 Mbit link, with 100 Mbit link the issue was not >> >> reproducible. >> >> >> >> Though, I recalling I was doing a bit more than your patch: I was >> >> also clearing the TX events in the ucce register before calling >> >> ucc_geth_tx, that way I was trying to avoid stale interrupts. That >> >> helped to increase an overall performance (not only responsiveness), >> >> but as I said my approach didn't pass the tests. >> >> >> >> I don't really think that your patch may cause this, but can you >> >> try netperf w/ this patch applied anyway? And see if it really >> >> doesn't cause any issues under stress? >> > >> > Does the line(in ucc_geth_tx()) look OK to you: >> > if ((bd == ugeth->txBd[txQ]) && (netif_queue_stopped(dev) == > 0)) >> > break; >> > >> > Sure does look fishy to me. >> >> There are two cases when txBd=ConfBd: the BD ring is full or empty. >> The condition used here ensures that it is the empty case. Because in >> hard_start_xmit, the queue will be stopped when the BD ring is full. >> Maybe some comment is needed here. > > But how do you know that the queue hasn't been stopped by someone else > than > the driver? > If it is stopped by higher layers, the if stmt will fail.
It looks like from existing code that only the driver can legally stop the queue. I'm not 100% sure though. Correct me if I'm wrong. - Leo _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
