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Groups > linux.kernel > #1529537
| From | David Miller <davem@davemloft.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. |
| Date | 2016-11-24 17:20 +0100 |
| Message-ID | <sH4UG-57A-27@gated-at.bofh.it> (permalink) |
| References | <sGDrr-3NA-9@gated-at.bofh.it> <sGY2X-lZ-25@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Pavel Machek <pavel@ucw.cz> Date: Thu, 24 Nov 2016 09:55:06 +0100 > Hi! > >> I'm debugging strange delays during transmit in stmmac driver. They >> seem to be present in 4.4 kernel (and older kernels, too). Workload is >> burst of udp packets being sent, pause, burst of udp packets, ... >> >> Test code is attached, I use these parameters for testing: >> >> ./udp-test raw 10.0.0.6 1234 1000 100 30 >> >> The delays seem to be related to coalescing: >> >> drivers/net/ethernet/stmicro/stmmac/common.h >> #define STMMAC_COAL_TX_TIMER 40000 >> #define STMMAC_MAX_COAL_TX_TICK 100000 >> #define STMMAC_TX_MAX_FRAMES 256 >> >> If I lower the parameters, delays are gone, but I get netdev watchdog >> backtrace followed by broken driver. >> >> Any ideas what is going on there? > > 4.9-rc6 still has the delays. With the > > #define STMMAC_COAL_TX_TIMER 1000 > #define STMMAC_TX_MAX_FRAMES 2 > > settings, delays go away, and driver still works. (It fails fairly > fast in 4.4). Good news. But the question still is: what is going on > there? 256 packets looks way too large for being a trigger for aborting the TX coalescing timer. Looking more deeply into this, the driver is using non-highres timers to implement the TX coalescing. This simply cannot work. 1 HZ, which is the lowest granularity of non-highres timers in the kernel, is variable as well as already too large of a delay for effective TX coalescing. I seriously think that the TX coalescing support should be ripped out or disabled entirely until it is implemented properly in this driver.
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stmmac ethernet in kernel 4.4: coalescing related pauses? Pavel Machek <pavel@ucw.cz> - 2016-11-23 12:00 +0100
stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-11-24 10:00 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-11-24 11:30 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@denx.de> - 2016-11-24 11:40 +0100
[PATCH] stmmac ethernet: unify locking Pavel Machek <pavel@ucw.cz> - 2016-11-24 11:50 +0100
[PATCH] stmmac ethernet: remove cut & paste code Pavel Machek <pavel@ucw.cz> - 2016-11-24 12:10 +0100
Re: [PATCH] stmmac ethernet: remove cut & paste code Joe Perches <joe@perches.com> - 2016-11-24 21:10 +0100
Re: [PATCH] stmmac ethernet: remove cut & paste code Pavel Machek <pavel@ucw.cz> - 2016-11-24 23:00 +0100
Re: [PATCH] stmmac ethernet: remove cut & paste code Joe Perches <joe@perches.com> - 2016-11-24 23:30 +0100
Re: [PATCH] stmmac ethernet: remove cut & paste code Pavel Machek <pavel@ucw.cz> - 2016-11-28 13:00 +0100
Re: [PATCH] stmmac ethernet: remove cut & paste code Joe Perches <joe@perches.com> - 2016-11-28 15:30 +0100
Re: [PATCH] stmmac ethernet: remove cut & paste code Pavel Machek <pavel@ucw.cz> - 2016-11-28 15:40 +0100
Re: [PATCH] stmmac ethernet: remove cut & paste code Joe Perches <joe@perches.com> - 2016-11-28 17:10 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. David Miller <davem@davemloft.net> - 2016-11-24 17:20 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-11-24 22:30 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Giuseppe CAVALLARO <peppe.cavallaro@st.com> - 2016-12-02 09:30 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-02 09:50 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Giuseppe CAVALLARO <peppe.cavallaro@st.com> - 2016-12-02 10:50 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-02 13:40 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Giuseppe CAVALLARO <peppe.cavallaro@st.com> - 2016-12-02 15:00 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-02 15:30 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Giuseppe CAVALLARO <peppe.cavallaro@st.com> - 2016-12-02 17:10 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-05 13:40 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-05 13:10 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-05 11:40 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. "Lino Sanfilippo" <LinoSanfilippo@gmx.de> - 2016-12-05 12:50 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-05 23:20 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Lino Sanfilippo <LinoSanfilippo@gmx.de> - 2016-12-05 23:40 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-05 23:50 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Lino Sanfilippo <LinoSanfilippo@gmx.de> - 2016-12-06 00:00 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Lino Sanfilippo <LinoSanfilippo@gmx.de> - 2016-12-06 00:20 +0100
Aw: Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. "Lino Sanfilippo" <LinoSanfilippo@gmx.de> - 2016-12-02 15:10 +0100
[RFC] Re: Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-07 13:40 +0100
Re: [RFC] Re: Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Lino Sanfilippo <lsanfil@marvell.com> - 2016-12-07 14:20 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Giuseppe CAVALLARO <peppe.cavallaro@st.com> - 2016-12-02 09:50 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-12-05 13:00 +0100
[PATCH] stmmac: fix comments, make debug output consistent Pavel Machek <pavel@ucw.cz> - 2016-11-28 13:00 +0100
Re: [PATCH] stmmac: fix comments, make debug output consistent David Miller <davem@davemloft.net> - 2016-11-30 02:00 +0100
Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses. Pavel Machek <pavel@ucw.cz> - 2016-11-28 13:20 +0100
[PATCH] stmmac: reduce code duplication getting basic descriptors Pavel Machek <pavel@ucw.cz> - 2016-11-28 13:20 +0100
Re: [PATCH] stmmac: reduce code duplication getting basic descriptors Alexandre Torgue <alexandre.torgue@st.com> - 2016-12-02 15:10 +0100
[PATCH] stmmac: simplify flag assignment Pavel Machek <pavel@ucw.cz> - 2016-11-30 12:50 +0100
Re: [PATCH] stmmac: simplify flag assignment David Miller <davem@davemloft.net> - 2016-12-01 21:30 +0100
stmmac: turn coalescing / NAPI off in stmmac Pavel Machek <pavel@ucw.cz> - 2016-12-01 23:50 +0100
Re: stmmac: turn coalescing / NAPI off in stmmac Giuseppe CAVALLARO <peppe.cavallaro@st.com> - 2016-12-02 09:50 +0100
Re: stmmac: turn coalescing / NAPI off in stmmac Pavel Machek <pavel@ucw.cz> - 2016-12-02 11:50 +0100
Re: stmmac: turn coalescing / NAPI off in stmmac Giuseppe CAVALLARO <peppe.cavallaro@st.com> - 2016-12-02 17:10 +0100
Re: stmmac: turn coalescing / NAPI off in stmmac Pavel Machek <pavel@ucw.cz> - 2016-12-05 12:50 +0100
Re: [PATCH] stmmac: simplify flag assignment Giuseppe CAVALLARO <peppe.cavallaro@st.com> - 2016-12-02 09:30 +0100
[PATCH] stmmac: cleanup documenation, make it match reality Pavel Machek <pavel@ucw.cz> - 2016-12-01 11:40 +0100
Re: [PATCH] stmmac: cleanup documenation, make it match reality David Miller <davem@davemloft.net> - 2016-12-03 21:10 +0100
[PATCH] stmmac: disable tx coalescing Pavel Machek <pavel@ucw.cz> - 2016-12-05 13:30 +0100
Re: stmmac ethernet in kernel 4.4: coalescing related pauses? Lino Sanfilippo <lsanfil@marvell.com> - 2016-11-28 14:10 +0100
Re: stmmac ethernet in kernel 4.4: coalescing related pauses? David Miller <davem@davemloft.net> - 2016-11-28 16:00 +0100
Re: stmmac ethernet in kernel 4.4: coalescing related pauses? Lino Sanfilippo <lsanfil@marvell.com> - 2016-11-28 16:40 +0100
Re: stmmac ethernet in kernel 4.4: coalescing related pauses? Eric Dumazet <eric.dumazet@gmail.com> - 2016-11-28 16:40 +0100
Re: stmmac ethernet in kernel 4.4: coalescing related pauses? Lino Sanfilippo <lsanfil@marvell.com> - 2016-11-28 17:00 +0100
Re: stmmac ethernet in kernel 4.4: coalescing related pauses? David Miller <davem@davemloft.net> - 2016-11-28 17:40 +0100
Re: stmmac ethernet in kernel 4.4: coalescing related pauses? Lino Sanfilippo <lsanfil@marvell.com> - 2016-11-28 18:10 +0100
Re: stmmac ethernet in kernel 4.4: coalescing related pauses? Pavel Machek <pavel@ucw.cz> - 2016-11-30 11:30 +0100
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