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From: Thomas Monjalon <thomas@monjalon.net>
To: Wisam Jaddo <wisamm@nvidia.com>
Cc: arybchenko@solarflare.com, suanmingm@nvidia.com,
	akozyrev@nvidia.com, dev@dpdk.org, david.marchand@redhat.com
Subject: Re: [dpdk-dev] [PATCH 3/4] app/flow-perf: change clock measurement functions
Date: Thu, 07 Jan 2021 15:49:45 +0100
Message-ID: <2781733.EIu5Jnm4Rv@thomas> (raw)
In-Reply-To: <20201126111543.16928-4-wisamm@nvidia.com>

26/11/2020 12:15, Wisam Jaddo:
> The clock() function is not good practice to use for multiple
> cores/threads, since it measures the CPU time used by the process
> and not the wall clock time, while when running through multiple
> cores/threads simultaneously, we can burn through CPU time much
> faster.
> 
> As a result this commit will change the way of measurement to use
> rd_tsc, and the results will be divided by the processor frequency.
> 
> Signed-off-by: Wisam Jaddo <wisamm@nvidia.com>
> Reviewed-by: Alexander Kozyrev <akozyrev@nvidia.com>
> Reviewed-by: Suanming Mou <suanmingm@nvidia.com>
> ---
> -	start_batch = clock();
> +	start_batch = rte_rdtsc();

Please could you try the generic wrapper rte_get_timer_cycles?
It should be the same (inline wrapper) when HPET is disabled.
rdtsc refer to an x86 instruction so I prefer a more generic API.

Can be a separate patch.
While at it, I believe more apps could be converted.



  reply	other threads:[~2021-01-07 14:49 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-26 11:15 [dpdk-dev] [PATCH 0/4] app/flow-perf: add multi threaded support Wisam Jaddo
2020-11-26 11:15 ` [dpdk-dev] [PATCH 1/4] app/flow-perf: refactor flows handler Wisam Jaddo
2020-11-26 11:15 ` [dpdk-dev] [PATCH 2/4] app/flow-perf: add multiple cores insertion and deletion Wisam Jaddo
2020-11-26 11:15 ` [dpdk-dev] [PATCH 3/4] app/flow-perf: change clock measurement functions Wisam Jaddo
2021-01-07 14:49   ` Thomas Monjalon [this message]
2020-11-26 11:15 ` [dpdk-dev] [PATCH 4/4] app/flow-perf: remove redundant items memset and vars Wisam Jaddo
2021-01-07 14:59 ` [dpdk-dev] [PATCH 0/4] app/flow-perf: add multi threaded support Thomas Monjalon

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