linux-kernel - Re: [PATCH 1/2] sched/deadline: add per rq tracking of admitted bandwidth

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Message-ID: <20160210093702.10c655be@gandalf.local.home>
Date:	Wed, 10 Feb 2016 09:37:02 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Juri Lelli <juri.lelli@....com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org,
	mingo@...hat.com, luca.abeni@...tn.it, vincent.guittot@...aro.org,
	wanpeng.li@...mail.com
Subject: Re: [PATCH 1/2] sched/deadline: add per rq tracking of admitted
 bandwidth

On Wed, 10 Feb 2016 11:32:58 +0000
Juri Lelli <juri.lelli@....com> wrote:

> Hi,
> 
> I've updated this patch since, with a bit more testing and talking with
> Luca in private, I realized that the previous version didn't manage
> switching back and forth from SCHED_DEADLINE correctly. Thanks a lot
> Luca for your feedback (even if not visible on the list).
> 
> I updated the testing branch accordingly and added a test to my tests
> that stresses switch-in/switch-out.
> 
> I don't particularly like the fact that we break the scheduling classes
> abstraction in __dl_overflow(), so I think a little bit of refactoring
> is still needed. But that can also happen afterwards, if we fix the
> problem with root domains.
> 
> Best,
> 
> - Juri
> 
> --->8---  
> 
> >From 62f70ca3051672dce209e8355cf5eddc9d825c2a Mon Sep 17 00:00:00 2001  
> From: Juri Lelli <juri.lelli@....com>
> Date: Sat, 6 Feb 2016 12:41:09 +0000
> Subject: [PATCH 1/2] sched/deadline: add per rq tracking of admitted bandwidth
> 


I applied this patch and patch 2 and hit this:

[ 2298.134284] ------------[ cut here ]------------
[ 2298.138933] WARNING: CPU: 4 PID: 0 at /home/rostedt/work/git/linux-trace.git/kernel/sched/sched.h:735 task_dead_dl+0xc5/0xd0()
[ 2298.150350] Modules linked in: ip6table_filter ip6_tables ebtable_nat ebtables xt_CHECKSUM iptable_mangle bridge stp llc bluetooth lockd grace snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core x86_pkg_temp_thermal snd_seq vhost_net snd_seq_device tun vhost macvtap macvlan coretemp iTCO_wdt snd_pcm hp_wmi rfkill kvm_intel sparse_keymap iTCO_vendor_support snd_timer snd acpi_cpufreq kvm i2c_i801 mei_me mei soundcore lpc_ich mfd_core irqbypass wmi serio_raw uinput i915 i2c_algo_bit e1000e drm_kms_helper crc32_pclmul ptp crc32c_intel drm pps_core i2c_core video sunrpc
[ 2298.207495] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 4.5.0-rc1-test+ #204
[ 2298.214392] Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
[ 2298.223371]  ffffffff81abc680 ffff880119433d68 ffffffff81411c3f 0000000000000000
[ 2298.230904]  ffffffff81abc680 ffff880119433da0 ffffffff810acf66 ffff88011eb16f40
[ 2298.238435]  ffff88001ee16200 ffffffff81fd4a00 00000000000aaaaa 0000000000000001
[ 2298.245958] Call Trace:
[ 2298.248431]  [<ffffffff81411c3f>] dump_stack+0x50/0xb1
[ 2298.253597]  [<ffffffff810acf66>] warn_slowpath_common+0x86/0xc0
[ 2298.259627]  [<ffffffff810ad05a>] warn_slowpath_null+0x1a/0x20
[ 2298.265490]  [<ffffffff810f92a5>] task_dead_dl+0xc5/0xd0
[ 2298.270828]  [<ffffffff810d833f>] finish_task_switch+0x16f/0x310
[ 2298.276871]  [<ffffffff810fa7f3>] ? pick_next_task_dl+0xb3/0x250
[ 2298.282906]  [<ffffffff817f07a3>] __schedule+0x3d3/0x9e0
[ 2298.288252]  [<ffffffff817f1001>] schedule+0x41/0xc0
[ 2298.293242]  [<ffffffff817f12c8>] schedule_preempt_disabled+0x18/0x30
[ 2298.299712]  [<ffffffff810fc974>] cpu_startup_entry+0x74/0x4e0
[ 2298.305573]  [<ffffffff8105d16f>] start_secondary+0x2bf/0x330
[ 2298.311347] ---[ end trace 732d16efabe456f1 ]---

It's the warning you added in __dl_sub_ac().

Things appear to still get all screwed up with cpusets and root
domains, but I can still recover with playing with load_balance.


-- Steve