From: "Morten Brørup" <mb@smartsharesystems.com>
To: "lihuisong (C)" <lihuisong@huawei.com>, <dev@dpdk.org>
Cc: <thomas@monjalon.net>, <ferruh.yigit@amd.com>,
<anatoly.burakov@intel.com>, <david.hunt@intel.com>,
<sivaprasad.tummala@amd.com>, <liuyonglong@huawei.com>
Subject: RE: [PATCH 0/2] introduce PM QoS interface
Date: Tue, 26 Mar 2024 09:27:35 +0100 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35E9F32E@smartserver.smartshare.dk> (raw)
In-Reply-To: <7378ca2b-b6f3-815c-1bbf-4765dffc0134@huawei.com>
> From: lihuisong (C) [mailto:lihuisong@huawei.com]
> Sent: Tuesday, 26 March 2024 03.12
>
> 在 2024/3/22 20:35, Morten Brørup 写道:
> >> From: lihuisong (C) [mailto:lihuisong@huawei.com]
> >> Sent: Friday, 22 March 2024 09.54
[...]
> >> For the case need PM QoS in DPDK, I think, it is better to set cpu
> >> latency to zero to prevent service thread from the deeper the idle
> state.
> > It would defeat the purpose (i.e. not saving sufficient amounts of
> power) if the CPU cannot enter a deeper idle state.
> Yes, it is not good for power.
> AFAIS, PM QoS is just to decrease the influence for performance.
> Anyway, if we set to zero, system can be into Cstates-0 at least.
> >
> > Personally, I would think a wake-up latency of up to 10 microseconds
> should be fine for must purposes.
> > Default Linux timerslack is 50 microseconds, so you could also use
> that value.
> How much CPU latency is ok. Maybe, we can give the decision to the
> application.
Yes, the application should decide the acceptable worst-case latency.
> Linux will collect all these QoS request and use the minimum latency.
> what do you think, Morten?
For the example application, you could use a value of 50 microseconds and refer to this value also being the default timerslack in Linux.
next prev parent reply other threads:[~2024-03-26 8:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-20 10:55 Huisong Li
2024-03-20 10:55 ` [PATCH 1/2] power: " Huisong Li
2024-03-20 10:55 ` [PATCH 2/2] examples/l3fwd-power: add PM QoS request configuration Huisong Li
2024-03-20 14:05 ` [PATCH 0/2] introduce PM QoS interface Morten Brørup
2024-03-21 3:04 ` lihuisong (C)
2024-03-21 13:30 ` Morten Brørup
2024-03-22 8:54 ` lihuisong (C)
2024-03-22 12:35 ` Morten Brørup
2024-03-26 2:11 ` lihuisong (C)
2024-03-26 8:27 ` Morten Brørup [this message]
2024-03-26 12:15 ` lihuisong (C)
2024-03-26 12:46 ` Morten Brørup
2024-03-29 1:59 ` lihuisong (C)
2024-03-22 17:55 ` Tyler Retzlaff
2024-03-26 2:20 ` lihuisong (C)
2024-03-26 16:04 ` Tyler Retzlaff
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