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From: "Kok, Auke" <auke-jan.h.kok@intel.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Shaohua Li <shaohua.li@intel.com>,
	lkml <linux-kernel@vger.kernel.org>,
	linux-pci <linux-pci@atrey.karlin.mff.cuni.cz>,
	Greg KH <greg@kroah.com>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
	Matthew Wilcox <matthew@wil.cx>
Subject: Re: [PATCH]PCIE ASPM support - takes 3
Date: Mon, 28 Jan 2008 15:14:50 -0800	[thread overview]
Message-ID: <479E61EA.8000702@intel.com> (raw)
In-Reply-To: <20080124172258.GA5447@ucw.cz>

Pavel Machek wrote:
> Hi!
> 
>> v3->v2, fixed the issues Matthew Wilcox raised.
>>
>> PCI Express ASPM defines a protocol for PCI Express components in the D0
>> state to reduce Link power by placing their Links into a low power state
>> and instructing the other end of the Link to do likewise. This
>> capability allows hardware-autonomous, dynamic Link power reduction
>> beyond what is achievable by software-only controlled power management.
>> However, The device should be configured by software appropriately.
>> Enabling ASPM will save power, but will introduce device latency.
> 
> How big is the latency? 1msec? 10msec? 100usec?

the latency is different for each device but the timing is negotiated and the
pci-e spec lists possible timings that can be used. The maximum is (I think...)
64usec but can be as low as 1 or 2 usec.

Auke

      parent reply	other threads:[~2008-01-28 23:23 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-18  1:56 Shaohua Li
2008-01-22 22:58 ` Greg KH
2008-01-23  2:20   ` Shaohua Li
2008-01-23 18:26     ` Greg KH
2008-01-24  2:21       ` Shaohua Li
2008-01-25 22:41         ` patch pci-pcie-aspm-support.patch added to gregkh-2.6 tree gregkh
2008-02-02 10:55           ` [bootup crash, -git] " Ingo Molnar
2008-02-02 18:51             ` Greg KH
2008-02-02 19:37               ` Ingo Molnar
2008-02-19  5:45               ` [bootup crash, -git] Re: patch pci-pcie-aspm-support.patchadded " Shaohua Li
2008-02-19 23:45                 ` Greg KH
2008-02-20  1:36                   ` Shaohua Li
2008-02-20  4:14                     ` Greg KH
2008-02-20  4:48                       ` Shaohua Li
2008-02-20  5:04                         ` Greg KH
2008-02-20  5:24                           ` Shaohua Li
2008-02-20  5:42                             ` Greg KH
2008-02-20  6:21                               ` Shaohua Li
2008-01-24 17:22 ` [PATCH]PCIE ASPM support - takes 3 Pavel Machek
2008-01-25  8:01   ` Li, Shaohua
2008-01-28 23:14   ` Kok, Auke [this message]

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