From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: Richard Frank <richard.frank-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Cc: David Brean <David.Brean-UdXhSnd/wVw@public.gmane.org>,
Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>,
linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: strong ordering for data registered memory
Date: Wed, 11 Nov 2009 16:13:38 -0700 [thread overview]
Message-ID: <20091111231338.GZ1966@obsidianresearch.com> (raw)
In-Reply-To: <4AFB3E6B.3080606-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
On Wed, Nov 11, 2009 at 05:44:59PM -0500, Richard Frank wrote:
> Would anyone like to through out the list of HCAs that do this... I
> can guess at a few... and can ask the vendors directly.. if not.. .
>
> It would be much nicer to not hardcode names of adapters.. but that won't
> stop us.. :)
Isn't it more complex than this? AFAIK the PCI-E standard does not
specify the order which data inside a single transfer becomes visible,
only how different transfers relate. To work on the most agressive
PCI-E system the HCA would have to transfer the last XX bytes as a
seperate PCI-E transaction without relaxed ordering.
This is the sort of thing that might start to matter on QPI and HT
memory-interleaved configurations. A multi-cache line transfer will be
split up and completed on different chips - it may not be fully
coherent 100% of the time.
Jason
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next prev parent reply other threads:[~2009-11-11 23:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-10 20:19 strong ordering for data registered memory David Brean
[not found] ` <4AF9CACE.8070700-UdXhSnd/wVw@public.gmane.org>
2009-11-11 17:57 ` Roland Dreier
[not found] ` <adaskclvta4.fsf-BjVyx320WGW9gfZ95n9DRSW4+XlvGpQz@public.gmane.org>
2009-11-11 18:16 ` Richard Frank
[not found] ` <4AFAFF7A.4090602-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2009-11-11 22:11 ` David Brean
[not found] ` <4AFB3677.6050603-UdXhSnd/wVw@public.gmane.org>
2009-11-11 22:44 ` Richard Frank
[not found] ` <4AFB3E6B.3080606-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2009-11-11 23:13 ` Jason Gunthorpe [this message]
[not found] ` <20091111231338.GZ1966-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2009-11-12 5:41 ` Dave Olson
2009-11-12 20:43 ` David Brean
2009-11-11 21:37 ` David Brean
[not found] ` <4AFB2EA5.4030804-UdXhSnd/wVw@public.gmane.org>
2009-11-11 23:06 ` Roland Dreier
[not found] ` <ada639gvezo.fsf-BjVyx320WGW9gfZ95n9DRSW4+XlvGpQz@public.gmane.org>
2009-11-12 20:42 ` David Brean
-- strict thread matches above, loose matches on Subject: below --
2009-11-12 21:51 Caitlin Bestler
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