linux-kernel - Re: [PATCH bpf] samples: bpf: fix summary per-sec stats in xdp_sample

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Message-Id: <163675020760.12842.17692151581487954557.git-patchwork-notify@kernel.org>
Date:   Fri, 12 Nov 2021 20:50:07 +0000
From:   patchwork-bot+netdevbpf@...nel.org
To:     Alexander Lobakin <alexandr.lobakin@...el.com>
Cc:     ast@...nel.org, daniel@...earbox.net, jesse.brandeburg@...el.com,
        maciej.fijalkowski@...el.com, michal.swiatkowski@...el.com,
        davem@...emloft.net, kuba@...nel.org, hawk@...nel.org,
        john.fastabend@...il.com, andrii@...nel.org, kafai@...com,
        songliubraving@...com, yhs@...com, kpsingh@...nel.org,
        memxor@...il.com, netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf] samples: bpf: fix summary per-sec stats in
 xdp_sample_user

Hello:

This patch was applied to bpf/bpf.git (master)
by Daniel Borkmann <daniel@...earbox.net>:

On Thu, 11 Nov 2021 22:57:03 +0100 you wrote:
> sample_summary_print() uses accumulated period to calculate and
> display per-sec averages. This period gets incremented by sampling
> interval each time a new sample is formed, and thus equals to the
> number of samples collected multiplied by this interval.
> However, the totals are being calculated differently, they receive
> current sample statistics already divided by the interval gotten as
> a difference between sample timestamps for better precision -- in
> other words, they are being incremented by the per-sec values each
> sample.
> This leads to the excessive division of summary per-secs when
> interval != 1 sec. It is obvious pps couldn't become two times
> lower just from picking a different sampling interval value:
> 
> [...]

Here is the summary with links:
  - [bpf] samples: bpf: fix summary per-sec stats in xdp_sample_user
    https://git.kernel.org/bpf/bpf/c/b51a6682d432

You are awesome, thank you!
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