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From: Jens Axboe <>
To: Jinpu Wang <>
Cc: Md Haris Iqbal <>,
	linux-block <>,
	Danil Kipnis <>
Subject: Re: [PATCH V6 0/3] block: add two statistic tables
Date: Mon, 19 Apr 2021 11:57:47 -0600
Message-ID: <> (raw)
In-Reply-To: <>

On 4/11/21 11:35 PM, Jinpu Wang wrote:
> On Fri, Apr 9, 2021 at 11:03 PM Jens Axboe <> wrote:
>> On 4/9/21 10:03 AM, Md Haris Iqbal wrote:
>>> Hi Jens,
>>> This version fixes the long lines in the code as per Christoph's comment.
>> I'd really like to see some solid justification for the addition,
>> though. I clicked the v1 link and it's got details on what you get out
>> of it, but not really the 'why' of reasoning for the feature. I mean,
>> you could feasibly have a blktrace based userspace solution. Just
>> wondering if that has been tried, I know that's what we do at Facebook
>> for example.
> Hi Jens,
> Thanks for the reply.
> For the use case of the additional stats, as a cloud provider, we
> often need to handle report from the customers regarding
> performance problem in a period of time in the past, so it's not
> feasible for us to run blktrace, customer workload could change from
> time to time, with the additional stats, we gather through all metrics
> using Prometheus, we can navigate to the period of time interested,
> to check if the performance matches the SLA, it also helps us to find
> the user IO pattern,  we can more easily reproduce.

My suggestion isn't to run just blktrace all the time, rather collect
the tracing info from there and store them away. Then you can go back
in time and see what is going on. Hence my questioning on adding this
new stat tracking, when it's already readily available to be consumed
by a small daemon that can continually track it in userspace.

Jens Axboe

  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-09 16:03 Md Haris Iqbal
2021-04-09 16:03 ` [PATCH V6 1/3] block: add io_extra_stats node Md Haris Iqbal
2021-04-09 16:03 ` [PATCH V6 2/3] block: add a statistic table for io latency Md Haris Iqbal
2021-04-09 16:03 ` [PATCH V6 3/3] block: add a statistic table for io sector Md Haris Iqbal
2021-04-09 21:03 ` [PATCH V6 0/3] block: add two statistic tables Jens Axboe
2021-04-12  5:35   ` Jinpu Wang
2021-04-19  6:37     ` Jinpu Wang
2021-04-19 17:57     ` Jens Axboe [this message]
2021-04-21  7:49       ` Jinpu Wang
2021-04-21 10:20         ` Pavel Begunkov
2021-04-21 11:50           ` Jinpu Wang
2021-04-21 11:55             ` Pavel Begunkov
2021-04-21 11:57               ` Jinpu Wang
2021-04-21 17:02                 ` Jens Axboe

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