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From: longtb5@viettel.com.vn
To: <users@dpdk.org>
Cc: <roy.fan.zhang@intel.com>, <cristian.dumitrescu@intel.com>
Subject: [dpdk-users] Understanding ip_pipeline thread headroom
Date: Thu,  1 Feb 2018 19:08:24 +0700 (ICT)	[thread overview]
Message-ID: <000001d39b55$d4acb490$7e061db0$@viettel.com.vn> (raw)

Hi,

The `thread` command in the ip_pipeline application is not documented. By
chance, I found in git log this interesting functionality.

> examples/ip_pipeline: measure CPU utilization
>
> This patch adds CPU utilization measurement and idle cycle rate
> computation to packet framework. The measurement is done by measuring
> the cycles spent while a thread pulls zero packet from RX queue. These
> cycles are treated as idle cycles (or headroom). A CLI command is added
> to display idle cycle rate of specific thread. The CLI command format is
> shown as following:
>
> t <thread_id> headroom

This command seems to be useful for power management. However I'm not quite
sure how to interpret the reported percentage of `thread headroom`. For
example, when I have ip_pipeline receiving packets at line rate, thread
headroom value for every pipeline module is close to 0%, as expected. But
when I send no packet at all, this value doesn't go up above 60%. In fact,
pipeline master reports a value of around 80%, when it doesn't receive or
process packets at all. Shouldn't it be 100%?

Please let me know if I misunderstood anything.

Thanks,
-BL

                 reply	other threads:[~2018-02-01 12:08 UTC|newest]

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