From: Roman Yeryomin <leroi.lists@gmail.com> To: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk> Cc: "Jesper Dangaard Brouer" <brouer@redhat.com>, "Eric Dumazet" <eric.dumazet@gmail.com>, "Felix Fietkau" <nbd@openwrt.org>, "Dave Taht" <dave.taht@gmail.com>, make-wifi-fast@lists.bufferbloat.net, "Rafał Miłecki" <zajec5@gmail.com>, ath10k <ath10k@lists.infradead.org>, "netdev@vger.kernel.org" <netdev@vger.kernel.org>, "codel@lists.bufferbloat.net" <codel@lists.bufferbloat.net>, "Jonathan Morton" <chromatix99@gmail.com> Subject: Re: OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] fq_codel_drop vs a udp flood) Date: Mon, 16 May 2016 01:47:30 +0300 [thread overview] Message-ID: <CACiydbLYFg7wgxdnzGGo1+_PSG=348x1c23nj96W8t6QhGKt_Q@mail.gmail.com> (raw) In-Reply-To: <572DBC21.10209@darbyshire-bryant.me.uk> On 7 May 2016 at 12:57, Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk> wrote: > > > On 06/05/16 10:42, Jesper Dangaard Brouer wrote: >> Hi Felix, >> >> This is an important fix for OpenWRT, please read! >> >> OpenWRT changed the default fq_codel sch->limit from 10240 to 1024, >> without also adjusting q->flows_cnt. Eric explains below that you must >> also adjust the buckets (q->flows_cnt) for this not to break. (Just >> adjust it to 128) >> >> Problematic OpenWRT commit in question: >> http://git.openwrt.org/?p=openwrt.git;a=patch;h=12cd6578084e >> 12cd6578084e ("kernel: revert fq_codel quantum override to prevent it from causing too much cpu load with higher speed (#21326)") > I 'pull requested' this to the lede-staging tree on github. > https://github.com/lede-project/staging/pull/11 > > One way or another Felix & co should see the change :-) If you would follow the white rabbit, you would see that it doesn't help >> >> >> I also highly recommend you cherry-pick this very recent commit: >> net-next: 9d18562a2278 ("fq_codel: add batch ability to fq_codel_drop()") >> https://git.kernel.org/davem/net-next/c/9d18562a227 >> >> This should fix very high CPU usage in-case fq_codel goes into drop mode. >> The problem is that drop mode was considered rare, and implementation >> wise it was chosen to be more expensive (to save cycles on normal mode). >> Unfortunately is it easy to trigger with an UDP flood. Drop mode is >> especially expensive for smaller devices, as it scans a 4K big array, >> thus 64 cache misses for small devices! >> >> The fix is to allow drop-mode to bulk-drop more packets when entering >> drop-mode (default 64 bulk drop). That way we don't suddenly >> experience a significantly higher processing cost per packet, but >> instead can amortize this. > I haven't done the above cherry-pick patch & backport patch creation for > 4.4/4.1/3.18 yet - maybe if $dayjob permits time and no one else beats > me to it :-) > > Kevin >
WARNING: multiple messages have this Message-ID (diff)
From: Roman Yeryomin <leroi.lists@gmail.com> To: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk> Cc: "Felix Fietkau" <nbd@openwrt.org>, "Eric Dumazet" <eric.dumazet@gmail.com>, make-wifi-fast@lists.bufferbloat.net, "Rafał Miłecki" <zajec5@gmail.com>, "Dave Taht" <dave.taht@gmail.com>, ath10k <ath10k@lists.infradead.org>, "netdev@vger.kernel.org" <netdev@vger.kernel.org>, "codel@lists.bufferbloat.net" <codel@lists.bufferbloat.net>, "Jesper Dangaard Brouer" <brouer@redhat.com>, "Jonathan Morton" <chromatix99@gmail.com> Subject: Re: OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] fq_codel_drop vs a udp flood) Date: Mon, 16 May 2016 01:47:30 +0300 [thread overview] Message-ID: <CACiydbLYFg7wgxdnzGGo1+_PSG=348x1c23nj96W8t6QhGKt_Q@mail.gmail.com> (raw) In-Reply-To: <572DBC21.10209@darbyshire-bryant.me.uk> On 7 May 2016 at 12:57, Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk> wrote: > > > On 06/05/16 10:42, Jesper Dangaard Brouer wrote: >> Hi Felix, >> >> This is an important fix for OpenWRT, please read! >> >> OpenWRT changed the default fq_codel sch->limit from 10240 to 1024, >> without also adjusting q->flows_cnt. Eric explains below that you must >> also adjust the buckets (q->flows_cnt) for this not to break. (Just >> adjust it to 128) >> >> Problematic OpenWRT commit in question: >> http://git.openwrt.org/?p=openwrt.git;a=patch;h=12cd6578084e >> 12cd6578084e ("kernel: revert fq_codel quantum override to prevent it from causing too much cpu load with higher speed (#21326)") > I 'pull requested' this to the lede-staging tree on github. > https://github.com/lede-project/staging/pull/11 > > One way or another Felix & co should see the change :-) If you would follow the white rabbit, you would see that it doesn't help >> >> >> I also highly recommend you cherry-pick this very recent commit: >> net-next: 9d18562a2278 ("fq_codel: add batch ability to fq_codel_drop()") >> https://git.kernel.org/davem/net-next/c/9d18562a227 >> >> This should fix very high CPU usage in-case fq_codel goes into drop mode. >> The problem is that drop mode was considered rare, and implementation >> wise it was chosen to be more expensive (to save cycles on normal mode). >> Unfortunately is it easy to trigger with an UDP flood. Drop mode is >> especially expensive for smaller devices, as it scans a 4K big array, >> thus 64 cache misses for small devices! >> >> The fix is to allow drop-mode to bulk-drop more packets when entering >> drop-mode (default 64 bulk drop). That way we don't suddenly >> experience a significantly higher processing cost per packet, but >> instead can amortize this. > I haven't done the above cherry-pick patch & backport patch creation for > 4.4/4.1/3.18 yet - maybe if $dayjob permits time and no one else beats > me to it :-) > > Kevin > _______________________________________________ ath10k mailing list ath10k@lists.infradead.org http://lists.infradead.org/mailman/listinfo/ath10k
next prev parent reply other threads:[~2016-05-15 22:47 UTC|newest] Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-05-01 3:41 fq_codel_drop vs a udp flood Dave Taht 2016-05-01 4:46 ` [Make-wifi-fast] " Jonathan Morton 2016-05-01 5:08 ` Ben Greear 2016-05-01 5:23 ` Dave Taht 2016-05-01 14:47 ` [Make-wifi-fast] " dpreed 2016-05-02 14:03 ` Roman Yeryomin 2016-05-02 18:40 ` Dave Taht 2016-05-05 13:55 ` Roman Yeryomin 2016-05-05 14:55 ` Roman Yeryomin 2016-05-02 19:47 ` David Lang 2016-05-01 17:59 ` [Codel] " Eric Dumazet 2016-05-01 18:20 ` Jonathan Morton 2016-05-01 18:46 ` Eric Dumazet 2016-05-01 19:55 ` Eric Dumazet 2016-05-02 7:47 ` Jesper Dangaard Brouer 2016-05-01 20:35 ` Jonathan Morton 2016-05-01 20:55 ` Eric Dumazet 2016-05-02 14:18 ` Roman Yeryomin 2016-05-02 15:07 ` Eric Dumazet 2016-05-02 15:43 ` Roman Yeryomin 2016-05-02 16:14 ` Eric Dumazet 2016-05-02 17:08 ` Dave Taht 2016-05-02 17:44 ` Eric Dumazet 2016-05-05 14:32 ` Roman Yeryomin 2016-05-05 14:53 ` Roman Yeryomin 2016-05-05 15:32 ` Dave Taht 2016-05-05 16:07 ` Roman Yeryomin 2016-05-05 16:59 ` Jonathan Morton 2016-05-05 17:39 ` Roman Yeryomin 2016-05-05 18:16 ` Dave Taht 2016-05-05 18:33 ` Dave Taht 2016-05-05 16:12 ` Eric Dumazet 2016-05-05 16:25 ` Roman Yeryomin 2016-05-05 16:42 ` Roman Yeryomin 2016-05-06 10:55 ` Roman Yeryomin 2016-05-05 19:23 ` Eric Dumazet 2016-05-05 19:41 ` Dave Taht 2016-05-06 8:41 ` moeller0 2016-05-06 11:33 ` Jesper Dangaard Brouer 2016-05-06 11:46 ` moeller0 2016-05-06 13:25 ` Eric Dumazet 2016-05-06 15:25 ` moeller0 2016-05-06 15:58 ` Eric Dumazet 2016-05-06 16:30 ` moeller0 2016-05-06 15:55 ` [PATCH net-next] fq_codel: add memory limitation per queue Eric Dumazet 2016-05-09 3:49 ` David Miller 2016-05-09 4:14 ` Cong Wang 2016-05-09 4:31 ` Eric Dumazet 2016-05-09 5:07 ` Cong Wang 2016-05-09 14:26 ` Eric Dumazet 2016-05-10 4:34 ` Cong Wang 2016-05-10 4:45 ` Eric Dumazet 2016-05-10 4:57 ` Cong Wang 2016-05-10 5:10 ` Eric Dumazet 2016-05-16 1:16 ` [PATCH net-next] fq_codel: fix memory limitation drift Eric Dumazet 2016-05-17 1:57 ` David Miller 2016-05-06 9:42 ` OpenWRT wrong adjustment of fq_codel defaults (Was: fq_codel_drop vs a udp flood) Jesper Dangaard Brouer 2016-05-06 9:42 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Jesper Dangaard Brouer 2016-05-06 12:47 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Jesper Dangaard Brouer 2016-05-06 12:47 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Jesper Dangaard Brouer 2016-05-06 18:43 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin 2016-05-06 18:43 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin 2016-05-06 18:56 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin 2016-05-06 18:56 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin 2016-05-06 19:43 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Dave Taht 2016-05-06 19:43 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Dave Taht 2016-05-15 22:34 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin 2016-05-15 22:34 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin 2016-05-15 23:07 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Eric Dumazet 2016-05-15 23:07 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Eric Dumazet 2016-05-15 23:27 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin 2016-05-15 23:27 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin 2016-05-16 8:12 ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: " David Lang 2016-05-16 8:12 ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " David Lang 2016-05-16 8:26 ` Roman Yeryomin 2016-05-16 8:26 ` Roman Yeryomin 2016-05-16 8:46 ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: " David Lang 2016-05-16 8:46 ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " David Lang 2016-05-16 10:34 ` [OpenWrt-Devel] [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: " Sebastian Moeller 2016-05-16 10:34 ` [OpenWrt-Devel] [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Sebastian Moeller 2016-05-16 8:14 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin 2016-05-16 8:14 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin 2016-05-16 14:23 ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: " Eric Dumazet 2016-05-16 14:23 ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Eric Dumazet 2016-05-16 16:04 ` Dave Taht 2016-05-16 16:04 ` Dave Taht 2016-05-16 19:46 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin 2016-05-16 19:46 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin 2016-05-07 9:57 ` Kevin Darbyshire-Bryant 2016-05-15 22:47 ` Roman Yeryomin [this message] 2016-05-15 22:47 ` Roman Yeryomin 2016-05-03 2:26 ` [Codel] fq_codel_drop vs a udp flood Dave Taht 2016-05-03 5:21 ` Dave Taht 2016-05-03 12:39 ` Agarwal, Anil 2016-05-03 12:50 ` Agarwal, Anil 2016-05-03 13:35 ` Eric Dumazet 2016-05-03 15:37 ` Agarwal, Anil 2016-05-03 17:37 ` Dave Taht 2016-05-03 17:54 ` Eric Dumazet 2016-05-03 18:11 ` Dave Taht 2016-05-03 13:20 ` Kevin Darbyshire-Bryant 2016-05-01 18:26 ` Dave Taht 2016-05-01 22:30 ` Eric Dumazet 2016-05-02 14:09 ` Roman Yeryomin 2016-05-02 15:04 ` Eric Dumazet 2016-05-02 15:42 ` Roman Yeryomin 2016-05-02 13:47 ` [Make-wifi-fast] " Roman Yeryomin 2016-05-02 15:01 ` Eric Dumazet
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