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Date:   Wed, 27 Jan 2021 22:13:46 +1100
From:   Balbir Singh <bsingharora@gmail.com>
To:     Weiping Zhang <zwp10758@gmail.com>
Cc:     sblbir@amazon.com, davem@davemloft.net,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v2] taskstats: add /proc/taskstats to fetch pid/tgid
 status
Message-ID: <20210127111346.GB59838@balbir-desktop>
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On Fri, Jan 22, 2021 at 10:07:50PM +0800, Weiping Zhang wrote:
> Hello Balbir Singh,
> 
> Could you help review this patch, thanks
> 
> On Mon, Dec 28, 2020 at 10:10 PM Weiping Zhang <zwp10758@gmail.com> wrote:
> >
> > Hi David,
> >
> > Could you help review this patch ?
> >
> > thanks
> >
> > On Fri, Dec 18, 2020 at 1:24 AM Weiping Zhang
> > <zhangweiping@didiglobal.com> wrote:
> > >
> > > If a program needs monitor lots of process's status, it needs two
> > > syscalls for every process. The first one is telling kernel which
> > > pid/tgid should be monitored by send a command(write socket) to kernel.
> > > The second one is read the statistics by read socket. This patch add
> > > a new interface /proc/taskstats to reduce two syscalls to one ioctl.
> > > The user just set the target pid/tgid to the struct taskstats.ac_pid,
> > > then kernel will collect statistics for that pid/tgid.
> > >
> > > Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com>

Could you elaborate on the overhead your seeing for the syscalls? I am not
in favour of adding new IOCTL's.

Balbir Singh.