From: ebiederm@xmission.com (Eric W. Biederman)
To: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: ast@fb.com, peterz@infradead.org,
lkml <linux-kernel@vger.kernel.org>,
acme@kernel.org, alexander.shishkin@linux.intel.com,
mingo@redhat.com, daniel@iogearbox.net, rostedt@goodmis.org,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
sargun@sargun.me, Aravinda Prasad <aravinda@linux.vnet.ibm.com>,
brendan.d.gregg@gmail.com, jolsa@redhat.com
Subject: Re: [PATCH v6 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info
Date: Fri, 17 Feb 2017 00:25:27 +1300 [thread overview]
Message-ID: <87zihmtm1k.fsf@xmission.com> (raw)
In-Reply-To: <148654268436.27983.5340774362600828412.stgit@hbathini.in.ibm.com> (Hari Bathini's message of "Wed, 08 Feb 2017 14:01:24 +0530")
> +/*
> + * The maximum size of the name of each namespace
> + */
> +#define NS_NAME_SIZE 8
> +
> +struct perf_ns_link_info {
> + char name[NS_NAME_SIZE];
> + __u64 dev;
> + __u64 ino;
> +};
Ugh. I missed the name the first time around.
That really looks like useless clutter. You already know the index so
the name doesn't add any information, so unless I am missing something
that name will just slow down the perf kernel implementation with
useless work.
The userspace reader can have the information just as reliably by
looking at the index and indexing into a table.
The set of namespaces changes slowly enough that this is not likely to
be a problem in practice. Especially as perf is released with the
kernel.
Plus who knows how long the name of the next namespace is going to be.
Eric
next prev parent reply other threads:[~2017-02-16 11:30 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-08 8:31 [PATCH v6 0/3] perf: add support for analyzing events for containers Hari Bathini
2017-02-08 8:31 ` [PATCH v6 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info Hari Bathini
2017-02-16 10:28 ` Peter Zijlstra
2017-02-16 10:36 ` Peter Zijlstra
2017-02-20 4:11 ` Hari Bathini
2017-02-16 11:25 ` Eric W. Biederman [this message]
2017-02-16 11:47 ` Peter Zijlstra
2017-02-20 4:16 ` Hari Bathini
2017-02-08 8:31 ` [PATCH v6 2/3] perf tool: " Hari Bathini
2017-02-08 12:57 ` Jiri Olsa
2017-02-08 12:57 ` Jiri Olsa
2017-02-08 12:57 ` Jiri Olsa
2017-02-21 14:03 ` Hari Bathini
2017-02-08 8:32 ` [PATCH v6 3/3] perf tool: add cgroup identifier entry in perf report Hari Bathini
2017-02-16 6:20 ` [PATCH v6 0/3] perf: add support for analyzing events for containers Eric W. Biederman
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