From: Robert Walker <robert.walker@arm.com>
To: Kim Phillips <kim.phillips@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mathieu.poirier@linaro.org,
mike.leach@linaro.org, mark.rutland@arm.com, will.deacon@arm.com,
robin.murphy@arm.com, sudeep.holla@arm.com,
frowand.list@gmail.com, robh@kernel.org, john.horley@arm.com
Subject: Re: [PATCH v2 21/27] coresight: Convert driver messages to dev_dbg
Date: Wed, 2 May 2018 09:25:38 +0100 [thread overview]
Message-ID: <019a4703-f51a-b402-7e92-c5045a17361a@arm.com> (raw)
In-Reply-To: <20180501225503.a55fb963795afb40163f3763@arm.com>
On 02/05/18 04:55, Kim Phillips wrote:
> On Tue, 1 May 2018 10:10:51 +0100
> Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
>
>> Convert component enable/disable messages from dev_info to dev_dbg.
>> This is required to prevent LOCKDEP splats when operating in perf
>> mode where we could be called with locks held to enable a coresight
> Can we see the splats? Doesn't lockdep turn itself off if it starts
> triggering too many splats?
>
>> path. If someone wants to really see the messages, they can always
>> enable it at runtime via dynamic_debug.
> Won't the splats still occur when the messages are enabled with
> dynamic_debug?
>
> So in effect this patch only tries to mitigate the splats, all the
> while making things harder for regular users that now have to recompile
> their kernels, in exchange for a very small convenience for kernel
> developers that happen to see a splat or two with DEBUG_LOCKDEP set?
>
> Not the greatest choice...How about moving the dev_infos outside of the
> locks instead?
>
> Thanks,
>
> Kim
The other reason for making these dev_dbg is performance - a message is
output each time a source / link / sink is enabled or disabled, so we
can get 20+ messages on each process switch when tracing with perf.
This has a significant effect on the runtime of the application being
traced.
Regards
Rob
WARNING: multiple messages have this Message-ID (diff)
From: robert.walker@arm.com (Robert Walker)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 21/27] coresight: Convert driver messages to dev_dbg
Date: Wed, 2 May 2018 09:25:38 +0100 [thread overview]
Message-ID: <019a4703-f51a-b402-7e92-c5045a17361a@arm.com> (raw)
In-Reply-To: <20180501225503.a55fb963795afb40163f3763@arm.com>
On 02/05/18 04:55, Kim Phillips wrote:
> On Tue, 1 May 2018 10:10:51 +0100
> Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
>
>> Convert component enable/disable messages from dev_info to dev_dbg.
>> This is required to prevent LOCKDEP splats when operating in perf
>> mode where we could be called with locks held to enable a coresight
> Can we see the splats? Doesn't lockdep turn itself off if it starts
> triggering too many splats?
>
>> path. If someone wants to really see the messages, they can always
>> enable it at runtime via dynamic_debug.
> Won't the splats still occur when the messages are enabled with
> dynamic_debug?
>
> So in effect this patch only tries to mitigate the splats, all the
> while making things harder for regular users that now have to recompile
> their kernels, in exchange for a very small convenience for kernel
> developers that happen to see a splat or two with DEBUG_LOCKDEP set?
>
> Not the greatest choice...How about moving the dev_infos outside of the
> locks instead?
>
> Thanks,
>
> Kim
The other reason for making these dev_dbg is performance - a message is
output each time a source / link / sink is enabled or disabled, so we
can get 20+ messages on each process switch when tracing with perf.?
This has a significant effect on the runtime of the application being
traced.
Regards
Rob
next prev parent reply other threads:[~2018-05-02 8:26 UTC|newest]
Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-01 9:10 [PATCH v2 00/27] coresight: TMC ETR backend support for perf Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 01/27] coresight: ETM: Add support for ARM Cortex-A73 Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 02/27] coresight: Cleanup device subtype struct Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 03/27] coresight: Add helper device type Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-03 17:00 ` Mathieu Poirier
2018-05-03 17:00 ` Mathieu Poirier
2018-05-05 9:56 ` Suzuki K Poulose
2018-05-05 9:56 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 04/27] coresight: Introduce support for Coresight Addrss Translation Unit Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-03 17:31 ` Mathieu Poirier
2018-05-03 17:31 ` Mathieu Poirier
2018-05-03 20:25 ` Mathieu Poirier
2018-05-03 20:25 ` Mathieu Poirier
2018-05-05 10:03 ` Suzuki K Poulose
2018-05-05 10:03 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 05/27] dts: bindings: Document device tree binding for CATU Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 13:10 ` Rob Herring
2018-05-01 13:10 ` Rob Herring
2018-05-03 17:42 ` Mathieu Poirier
2018-05-03 17:42 ` Mathieu Poirier
2018-05-08 15:40 ` Suzuki K Poulose
2018-05-08 15:40 ` Suzuki K Poulose
2018-05-11 16:05 ` Rob Herring
2018-05-11 16:05 ` Rob Herring
2018-05-14 14:42 ` Mathieu Poirier
2018-05-14 14:42 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 06/27] coresight: tmc etr: Disallow perf mode temporarily Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 07/27] coresight: tmc: Hide trace buffer handling for file read Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-03 19:50 ` Mathieu Poirier
2018-05-03 19:50 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 08/27] coresight: tmc-etr: Do not clean trace buffer Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 09/27] coresight: Add helper for inserting synchronization packets Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 10/27] dts: bindings: Restrict coresight tmc-etr scatter-gather mode Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 13:13 ` Rob Herring
2018-05-01 13:13 ` Rob Herring
2018-05-03 20:32 ` Mathieu Poirier
2018-05-03 20:32 ` Mathieu Poirier
2018-05-04 22:56 ` Rob Herring
2018-05-04 22:56 ` Rob Herring
2018-05-08 15:48 ` Suzuki K Poulose
2018-05-08 15:48 ` Suzuki K Poulose
2018-05-08 17:34 ` Rob Herring
2018-05-08 17:34 ` Rob Herring
2018-05-01 9:10 ` [PATCH v2 11/27] dts: juno: Add scatter-gather support for all revisions Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 12/27] coresight: tmc-etr: Allow commandline option to override SG use Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-03 20:40 ` Mathieu Poirier
2018-05-03 20:40 ` Mathieu Poirier
2018-05-08 15:49 ` Suzuki K Poulose
2018-05-08 15:49 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 13/27] coresight: Add generic TMC sg table framework Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-04 17:35 ` Mathieu Poirier
2018-05-04 17:35 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 14/27] coresight: Add support for TMC ETR SG unit Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 15/27] coresight: tmc-etr: Make SG table circular Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 16/27] coresight: tmc-etr: Add transparent buffer management Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-07 17:20 ` Mathieu Poirier
2018-05-07 17:20 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 17/27] coresight: etr: Add support for save restore buffers Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-07 17:48 ` Mathieu Poirier
2018-05-07 17:48 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 18/27] coresight: catu: Add support for scatter gather tables Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-07 20:25 ` Mathieu Poirier
2018-05-07 20:25 ` Mathieu Poirier
2018-05-08 15:56 ` Suzuki K Poulose
2018-05-08 15:56 ` Suzuki K Poulose
2018-05-08 16:13 ` Mathieu Poirier
2018-05-08 16:13 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 19/27] coresight: catu: Plug in CATU as a backend for ETR buffer Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-07 22:02 ` Mathieu Poirier
2018-05-07 22:02 ` Mathieu Poirier
2018-05-08 16:21 ` Suzuki K Poulose
2018-05-08 16:21 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 20/27] coresight: tmc: Add configuration support for trace buffer size Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 21/27] coresight: Convert driver messages to dev_dbg Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-02 3:55 ` Kim Phillips
2018-05-02 3:55 ` Kim Phillips
2018-05-02 8:25 ` Robert Walker [this message]
2018-05-02 8:25 ` Robert Walker
2018-05-02 13:52 ` Robin Murphy
2018-05-02 13:52 ` Robin Murphy
2018-05-10 13:36 ` Suzuki K Poulose
2018-05-10 13:36 ` Suzuki K Poulose
2018-05-07 22:28 ` Mathieu Poirier
2018-05-07 22:28 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 22/27] coresight: tmc-etr: Track if the device is coherent Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 23/27] coresight: tmc-etr: Handle driver mode specific ETR buffers Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-08 17:18 ` Mathieu Poirier
2018-05-08 17:18 ` Mathieu Poirier
2018-05-08 21:51 ` Suzuki K Poulose
2018-05-08 21:51 ` Suzuki K Poulose
2018-05-09 17:12 ` Mathieu Poirier
2018-05-09 17:12 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 24/27] coresight: tmc-etr: Relax collection of trace from sysfs mode Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-07 22:54 ` Mathieu Poirier
2018-05-07 22:54 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 25/27] coresight: etr_buf: Add helper for padding an area of trace data Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-08 17:34 ` Mathieu Poirier
2018-05-08 17:34 ` Mathieu Poirier
2018-05-01 9:10 ` [PATCH v2 26/27] coresight: perf: Remove reset_buffer call back for sinks Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-08 19:42 ` Mathieu Poirier
2018-05-08 19:42 ` Mathieu Poirier
2018-05-11 16:35 ` Suzuki K Poulose
2018-05-11 16:35 ` Suzuki K Poulose
2018-05-01 9:10 ` [PATCH v2 27/27] coresight: etm-perf: Add support for ETR backend Suzuki K Poulose
2018-05-01 9:10 ` Suzuki K Poulose
2018-05-08 22:04 ` Mathieu Poirier
2018-05-08 22:04 ` Mathieu Poirier
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