From: Juergen Gross <jgross@suse.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
Julien Grall <julien.grall@arm.com>,
xen-devel@lists.xenproject.org
Subject: Re: [Xen-devel] [PATCH v6 4/5] xen: add per-cpu buffer option to debugtrace
Date: Mon, 9 Sep 2019 10:15:03 +0200 [thread overview]
Message-ID: <394d9dbd-c2b5-7219-7b78-ddfbd65a9780@suse.com> (raw)
In-Reply-To: <1ba88fc4-dc73-7fc1-d390-c7373a6db250@suse.com>
On 09.09.19 10:04, Jan Beulich wrote:
> On 09.09.2019 09:59, Jan Beulich wrote:
>> On 09.09.2019 09:35, Juergen Gross wrote:
>>> debugtrace is normally writing trace entries into a single trace
>>> buffer. There are cases where this is not optimal, e.g. when hunting
>>> a bug which requires writing lots of trace entries and one cpu is
>>> stuck. This will result in other cpus filling the trace buffer and
>>> finally overwriting the interesting trace entries of the hanging cpu.
>>>
>>> In order to be able to debug such situations add the capability to use
>>> per-cpu trace buffers. This can be selected by specifying the
>>> debugtrace boot parameter with the modifier "cpu:", like:
>>>
>>> debugtrace=cpu:16
>>>
>>> At the same time switch the parsing function to accept size modifiers
>>> (e.g. 4M or 1G).
>>>
>>> Printing out the trace entries is done for each buffer in order to
>>> minimize the effort needed during printing. As each entry is prefixed
>>> with its sequence number sorting the entries can easily be done when
>>> analyzing them.
>>>
>>> Signed-off-by: Juergen Gross <jgross@suse.com>
>>
>> Reviewed-by: Jan Beulich <jbeulich@suse.com>
>
> Oh, no - I have to take this back. Looking at patch 5 I notice
> that you now only ever write last_cpu; you must have lost its
> consumer.
Oh, indeed. Thanks for spotting that. Will send out a corrected patch
soon.
Juergen
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next prev parent reply other threads:[~2019-09-09 8:15 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-09 7:35 [Xen-devel] [PATCH v6 0/5] xen: debugtrace cleanup and per-cpu buffer support Juergen Gross
2019-09-09 7:35 ` [Xen-devel] [PATCH v6 1/5] xen: fix debugtrace clearing Juergen Gross
2019-09-09 7:53 ` Jan Beulich
2019-09-09 8:11 ` Jan Beulich
2019-09-09 8:19 ` Juergen Gross
2019-09-09 7:35 ` [Xen-devel] [PATCH v6 2/5] xen: move debugtrace coding to common/debugtrace.c Juergen Gross
2019-09-09 7:35 ` [Xen-devel] [PATCH v6 3/5] xen: refactor debugtrace data Juergen Gross
2019-09-09 7:35 ` [Xen-devel] [PATCH v6 4/5] xen: add per-cpu buffer option to debugtrace Juergen Gross
2019-09-09 7:59 ` Jan Beulich
2019-09-09 8:04 ` Jan Beulich
2019-09-09 8:15 ` Juergen Gross [this message]
2019-09-09 7:35 ` [Xen-devel] [PATCH v6 5/5] xen: add debugtrace entry when entry count is wrapping Juergen Gross
2019-09-09 8:19 ` Jan Beulich
2019-09-09 8:22 ` Juergen Gross
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