linux-kernel - Re: [PATCH v5 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info

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Date:   Fri, 20 Jan 2017 21:26:32 +0530
From:   Hari Bathini <hbathini@...ux.vnet.ibm.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     ast@...com, lkml <linux-kernel@...r.kernel.org>, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, mingo@...hat.com,
        daniel@...earbox.net, rostedt@...dmis.org,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        ebiederm@...ssion.com, sargun@...gun.me,
        Aravinda Prasad <aravinda@...ux.vnet.ibm.com>,
        brendan.d.gregg@...il.com, jolsa@...hat.com
Subject: Re: [PATCH v5 1/3] perf: add PERF_RECORD_NAMESPACES to include
 namespaces related info

Hi Peter,


On Wednesday 18 January 2017 07:56 PM, Peter Zijlstra wrote:
> On Tue, Jan 17, 2017 at 07:47:22PM +0530, Hari Bathini wrote:
>> With the advert of container technologies like docker, that depend
>> on namespaces for isolation, there is a need for tracing support for
>> namespaces. This patch introduces new PERF_RECORD_NAMESPACES event
>> for tracing based on namespaces related info.
> This fails to mention the whole namespace of namespaces issue Eric

IIUC, Eric wanted to have device info saved for each namespace separately
to avoid the need for a namespace of namespaces in future.

> brought up. Where are we on that, and or why isn't it required?


I did address that in v4 and haven't changed it in v5.
I am not sure if it needs any mentioning in the changelog..

>> +/*
>> + * The maximum size of the name of each namespace
>> + */
>> +#define NS_NAME_SIZE				8
>> +
>> +struct perf_ns_link_info {
>> +	char	name[NS_NAME_SIZE];
> Do we really need a name? why?

Helps print new namespaces info along with name without any changes in
perf tool. Avoids hard-coding names too..

Thanks
Hari