From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oded Gabbay Subject: Re: Re: [PATCH] net: less interrupt masking in NAPI Date: Sat, 10 Jan 2015 22:27:58 +0200 Message-ID: <1420921678-18609-1-git-send-email-oded.gabbay@amd.com> References: <20141103.122538.387451917276174830.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain Cc: , To: , Return-path: Received: from mail-bl2on0143.outbound.protection.outlook.com ([65.55.169.143]:24146 "EHLO na01-bl2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755778AbbAJWBb (ORCPT ); Sat, 10 Jan 2015 17:01:31 -0500 In-Reply-To: <20141103.122538.387451917276174830.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 2014/11/4 1:25, David Miller wrote: > From: Eric Dumazet > Date: Sun, 02 Nov 2014 06:19:33 -0800 > >> From: Eric Dumazet >> >> net_rx_action() can mask irqs a single time to transfert sd->poll_list >> into a private list, for a very short duration. >> >> Then, napi_complete() can avoid masking irqs again, >> and net_rx_action() only needs to mask irq again in slow path. >> >> This patch removes 2 couples of irq mask/unmask per typical NAPI run, >> more if multiple napi were triggered. >> >> Note this also allows to give control back to caller (do_softirq()) >> more often, so that other softirq handlers can be called a bit earlier, >> or ksoftirqd can be wakeup earlier under pressure. >> >> This was developed while testing an alternative to RX interrupt >> mitigation to reduce latencies while keeping or improving GRO >> aggregation on fast NIC. >> >> Idea is to test napi->gro_list at the end of a napi->poll() and >> reschedule one NAPI poll, but after servicing a full round of >> softirqs (timers, TX, rcu, ...). This will be allowed only if softirq >> is currently serviced by idle task or ksoftirqd, and resched not needed. >> >> Signed-off-by: Eric Dumazet > > Also applied, thanks Eric. Hi, Unfortunately, this patch breaks my "Qualcomm Atheros AR8161 Gigabit Ethernet (rev 10)" Ethernet controller, which is handled by the alx network driver. ogabbay@odedg-ubuntu:~$ lspci -s 01:00.0 -k 01:00.0 Ethernet controller: Qualcomm Atheros AR8161 Gigabit Ethernet (rev 10) Subsystem: Qualcomm Atheros Device 1071 Kernel driver in use: alx I have this controller on a mobile platform which I use to test amdkfd on Kaveri AMD APU and from 3.19-rc1, the network stopped working when trying to transfer files through scp or nfs. I bisected the kernel (from 3.18.0 to 3.19-rc1) and reached this patch. Here is the log of the bisect: git bisect start # bad: [97bf6af1f928216fd6c5a66e8a57bfa95a659672] Linux 3.19-rc1 git bisect bad 97bf6af1f928216fd6c5a66e8a57bfa95a659672 # good: [b2776bf7149bddd1f4161f14f79520f17fc1d71d] Linux 3.18 git bisect good b2776bf7149bddd1f4161f14f79520f17fc1d71d # bad: [70e71ca0af244f48a5dcf56dc435243792e3a495] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next git bisect bad 70e71ca0af244f48a5dcf56dc435243792e3a495 # good: [e28870f9b3e92cd3570925089c6bb789c2603bc4] Merge tag 'backlight-for-linus-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight git bisect good e28870f9b3e92cd3570925089c6bb789c2603bc4 # bad: [450fa21942fe2c37f0c9f52d1a33bbc081eee288] sh_eth: Remove redundant alignment adjustment git bisect bad 450fa21942fe2c37f0c9f52d1a33bbc081eee288 # bad: [5c8d19da950861d0482abc0ac3481acca34b008f] e100e: use netdev_rss_key_fill() helper git bisect bad 5c8d19da950861d0482abc0ac3481acca34b008f # good: [bf515fb11ab539c76d04f0e3c5216ed41f41d81f] Merge tag 'mac80211-next-for-john-2014-11-04' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next git bisect good bf515fb11ab539c76d04f0e3c5216ed41f41d81f # bad: [2c99cd914d4fed9160d98849c9dd38034616768e] Merge branch 'amd-xgbe-next' git bisect bad 2c99cd914d4fed9160d98849c9dd38034616768e # good: [3d762a0f0ab9cb4a6b5993db3ce56c92f9f90ab2] net: dsa: Add support for reading switch registers with ethtool git bisect good 3d762a0f0ab9cb4a6b5993db3ce56c92f9f90ab2 # bad: [8ce0c8254f15229aa99fc6c04141f28c446e5f8c] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/net-next git bisect bad 8ce0c8254f15229aa99fc6c04141f28c446e5f8c # good: [f0c65567b3c1b23f79e8a49139580a3872a68d1f] Merge branch 'sunvnet-multi-tx-queue' git bisect good f0c65567b3c1b23f79e8a49139580a3872a68d1f # bad: [547f2735c20023d7b50a791b1b17cacb652e9237] Merge branch 'mlx4-next' git bisect bad 547f2735c20023d7b50a791b1b17cacb652e9237 # good: [4cdb1e2e3d3495423db558d3bb7ed11d66aabce7] net: shrink struct softnet_data git bisect good 4cdb1e2e3d3495423db558d3bb7ed11d66aabce7 # bad: [0a98455666ec87378148a1dde97f1ce5baf75a64] net/mlx4_core: Protect port type setting by mutex git bisect bad 0a98455666ec87378148a1dde97f1ce5baf75a64 # bad: [6e8066999800d90d52af5c84ac49ebf683d14cdc] net/mlx4_core: Prevent VF from changing port configuration git bisect bad 6e8066999800d90d52af5c84ac49ebf683d14cdc # bad: [d75b1ade567ffab085e8adbbdacf0092d10cd09c] net: less interrupt masking in NAPI git bisect bad d75b1ade567ffab085e8adbbdacf0092d10cd09c # first bad commit: [d75b1ade567ffab085e8adbbdacf0092d10cd09c] net: less interrupt masking in NAPI Could you please solve this issue as it renders my board quite useless. If you need more info, please ask. Thanks, Oded