From: Tom Talpey <tom@talpey.com>
To: 'Christoph Hellwig' <hch@infradead.org>,
Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>,
Steve Wise <swise@opengridcomputing.com>,
dledford@redhat.com, sagig@mellanox.com, ogerlitz@mellanox.com,
roid@mellanox.com, linux-rdma@vger.kernel.org, eli@mellanox.com,
target-devel@vger.kernel.org, linux-nfs@vger.kernel.org,
trond.myklebust@primarydata.com, bfields@fieldses.org,
Oren Duer <oren@mellanox.com>
Subject: Re: [PATCH V3 1/5] RDMA/core: Transport-independent access flags
Date: Mon, 13 Jul 2015 15:36:44 -0400 [thread overview]
Message-ID: <55A4134C.2040301@talpey.com> (raw)
In-Reply-To: <20150711102538.GB14741@infradead.org>
On 7/11/2015 6:25 AM, 'Christoph Hellwig' wrote:
> I think what we need to support for now is FRMR as the primary target,
> and FMR as a secondar[y].
FMR is a *very* bad choice, for several reasons.
1) It's not supported by very many devices, in fact it might even
be thought to be obsolete.
2) It does not protect on byte boundaries, therefore it is unsafe
to use for anything but page-sized, page-aligned RDMA operations.
3) It is a synchronous API, i.e. it is not work-request based and
therefore is not very high performance.
4) It sometimes is used with a "pool", which defers deregistration
in the hopes of amortizing overhead. However, this deferral further
increases the risk of remote access, including altering of memory
contents after the fact.
Personally, I'd recommend ib_get_phys_mr() over FMR. It at least
doesn't suffer from issues 1, 2 and 4.
next prev parent reply other threads:[~2015-07-13 19:36 UTC|newest]
Thread overview: 138+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-05 23:21 [PATCH V3 0/5] Transport-independent MRs Steve Wise
2015-07-05 23:22 ` [PATCH V3 1/5] RDMA/core: Transport-independent access flags Steve Wise
2015-07-06 5:25 ` Christoph Hellwig
2015-07-06 14:23 ` Steve Wise
2015-07-07 8:58 ` 'Christoph Hellwig'
[not found] ` <20150705232158.12029.25472.stgit-PBeJgSbIpn97NCTnQtmixQ@public.gmane.org>
2015-07-06 7:09 ` Haggai Eran
[not found] ` <559A2991.3040304-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2015-07-06 14:29 ` Steve Wise
2015-07-07 14:17 ` Steve Wise
2015-07-07 14:34 ` Haggai Eran
2015-07-07 14:46 ` Steve Wise
2015-07-07 15:07 ` Haggai Eran
2015-07-06 7:53 ` Sagi Grimberg
2015-07-06 14:37 ` Steve Wise
2015-07-06 16:17 ` Sagi Grimberg
2015-07-06 16:55 ` Steve Wise
2015-07-07 9:00 ` Christoph Hellwig
[not found] ` <20150707090001.GB11736-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-07 9:14 ` Sagi Grimberg
[not found] ` <559B9891.8060907-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-07 14:05 ` Steve Wise
2015-07-07 16:17 ` Jason Gunthorpe
[not found] ` <20150707161751.GA623-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-07 16:27 ` Sagi Grimberg
[not found] ` <559BFE03.4020709-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-07 21:36 ` Jason Gunthorpe
2015-07-08 7:29 ` Sagi Grimberg
[not found] ` <559CD174.4040901-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-08 8:13 ` 'Christoph Hellwig'
[not found] ` <20150708081320.GB24203-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-08 10:05 ` Sagi Grimberg
[not found] ` <559CF5E8.6080000-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-08 10:20 ` 'Christoph Hellwig'
[not found] ` <20150708102035.GA28421-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-08 11:08 ` Sagi Grimberg
[not found] ` <559D0498.9050809-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-08 17:14 ` Hefty, Sean
2015-07-09 8:46 ` Sagi Grimberg
2015-07-09 13:52 ` Chuck Lever
2015-07-10 19:34 ` Christoph Hellwig
2015-07-12 7:49 ` Sagi Grimberg
2015-07-13 16:50 ` Jason Gunthorpe
2015-07-14 8:06 ` Sagi Grimberg
[not found] ` <55A4C2FA.9060707-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-14 12:24 ` Tom Talpey
[not found] ` <55A4FF93.4090406-CLs1Zie5N5HQT0dZR+AlfA@public.gmane.org>
2015-07-14 13:21 ` Sagi Grimberg
2015-07-23 0:43 ` Hefty, Sean
2015-07-08 19:08 ` Jason Gunthorpe
[not found] ` <20150708190842.GB11740-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-08 20:32 ` 'Christoph Hellwig'
2015-07-09 0:03 ` Jason Gunthorpe
[not found] ` <20150709000337.GE16812-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-09 8:00 ` 'Christoph Hellwig'
2015-07-09 8:58 ` Sagi Grimberg
2015-07-09 22:18 ` Doug Ledford
2015-07-09 22:53 ` Jason Gunthorpe
2015-07-10 13:22 ` Tom Talpey
[not found] ` <559FC710.1050307-CLs1Zie5N5HQT0dZR+AlfA@public.gmane.org>
2015-07-10 16:11 ` Jason Gunthorpe
2015-07-10 17:56 ` Doug Ledford
2015-07-10 18:34 ` Chuck Lever
2015-07-10 18:42 ` Tom Talpey
[not found] ` <55A01225.9000000-CLs1Zie5N5HQT0dZR+AlfA@public.gmane.org>
2015-07-10 19:54 ` Jason Gunthorpe
2015-07-10 20:48 ` Jason Gunthorpe
[not found] ` <20150710195420.GA31500-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-10 22:33 ` Doug Ledford
2015-07-11 10:17 ` 'Christoph Hellwig'
[not found] ` <20150711101736.GA14741-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-13 16:57 ` Jason Gunthorpe
2015-07-14 7:25 ` 'Christoph Hellwig'
2015-07-14 9:05 ` Sagi Grimberg
2015-07-14 15:35 ` 'Christoph Hellwig'
2015-07-14 17:26 ` Jason Gunthorpe
[not found] ` <20150714172655.GB24403-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-15 7:10 ` Sagi Grimberg
2015-07-10 22:30 ` Doug Ledford
2015-07-10 20:57 ` Jason Gunthorpe
[not found] ` <20150710205706.GA7883-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-10 22:27 ` Doug Ledford
[not found] ` <20150710233417.GA8919@obsidianresearch.com>
[not found] ` <20150710233417.GA8919-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-11 3:10 ` Doug Ledford
[not found] ` <55A0891F.4050105-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2015-07-13 17:18 ` Jason Gunthorpe
2015-07-13 22:23 ` Tom Talpey
2015-07-11 16:37 ` Steve Wise
[not found] ` <CCB6E837-88FF-4DBB-976D-4CF56396A1A1-/Yg/VP3ZvrM@public.gmane.org>
2015-07-12 10:46 ` Sagi Grimberg
[not found] ` <55A24571.60902-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-14 19:25 ` Steve Wise
2015-07-14 19:29 ` Jason Gunthorpe
[not found] ` <20150714192941.GA26292-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-14 19:32 ` Steve Wise
2015-07-14 19:37 ` Jason Gunthorpe
2015-07-14 19:55 ` 'Christoph Hellwig'
2015-07-14 20:10 ` Steve Wise
[not found] ` <20150714195511.GB7716-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-14 20:29 ` Jason Gunthorpe
[not found] ` <20150714202943.GB26927-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-14 20:40 ` Steve Wise
2015-07-14 20:44 ` Jason Gunthorpe
[not found] ` <20150714204442.GD26927-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-14 20:54 ` Steve Wise
2015-07-14 20:59 ` Jason Gunthorpe
2015-07-14 20:50 ` Tom Talpey
2015-07-15 8:47 ` Sagi Grimberg
[not found] ` <55A61E38.20201-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-15 12:19 ` 'Christoph Hellwig'
[not found] ` <20150715121926.GB14993-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-15 19:17 ` Jason Gunthorpe
2015-07-15 6:50 ` 'Christoph Hellwig'
[not found] ` <20150715065057.GA22113-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-15 19:12 ` Jason Gunthorpe
[not found] ` <20150715191257.GF23588-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-16 6:41 ` Jason Gunthorpe
2015-07-16 8:04 ` 'Christoph Hellwig'
[not found] ` <20150716080402.GC9093-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-16 16:13 ` Jason Gunthorpe
2015-07-14 20:46 ` Tom Talpey
2015-07-14 19:45 ` 'Christoph Hellwig'
[not found] ` <20150714194512.GA25887-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-14 19:57 ` Jason Gunthorpe
2015-07-14 19:58 ` Steve Wise
2015-07-14 20:41 ` Jason Gunthorpe
[not found] ` <20150714204145.GC26927-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-14 20:51 ` Steve Wise
2015-07-14 21:01 ` Steve Wise
2015-07-14 21:14 ` Jason Gunthorpe
2015-07-23 18:53 ` Hefty, Sean
[not found] ` <1828884A29C6694DAF28B7E6B8A82373A901C9A5-P5GAC/sN6hkd3b2yrw5b5LfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2015-07-23 19:03 ` Steve Wise
2015-07-23 23:30 ` Hefty, Sean
[not found] ` <1828884A29C6694DAF28B7E6B8A82373A901DB80-P5GAC/sN6hkd3b2yrw5b5LfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2015-07-23 23:53 ` Jason Gunthorpe
[not found] ` <20150723235310.GA20537-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-24 0:18 ` Hefty, Sean
2015-07-24 4:46 ` Jason Gunthorpe
[not found] ` <20150708203205.GA21847-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-08 20:37 ` 'Christoph Hellwig'
2015-07-09 8:47 ` Sagi Grimberg
2015-07-08 21:38 ` Tom Talpey
2015-07-08 23:36 ` Jason Gunthorpe
2015-07-09 11:02 ` Sagi Grimberg
[not found] ` <559E54AB.2010905-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-09 17:01 ` Jason Gunthorpe
2015-07-09 20:00 ` Tom Talpey
2015-07-09 21:16 ` Jason Gunthorpe
[not found] ` <20150709170142.GA21921-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-10 8:55 ` kernel memory registration (was: RDMA/core: Transport-independent access flags) Sagi Grimberg
[not found] ` <559F8881.7070308-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-10 16:35 ` Jason Gunthorpe
2015-07-11 10:31 ` 'Christoph Hellwig'
[not found] ` <20150711103153.GC14741-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-13 16:46 ` Jason Gunthorpe
[not found] ` <20150713164652.GC23832-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-14 8:24 ` kernel memory registration Sagi Grimberg
[not found] ` <55A4C73A.7080001-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-14 17:24 ` Jason Gunthorpe
2015-07-11 10:25 ` [PATCH V3 1/5] RDMA/core: Transport-independent access flags 'Christoph Hellwig'
2015-07-13 16:35 ` Jason Gunthorpe
2015-07-13 19:36 ` Tom Talpey [this message]
2015-07-13 20:15 ` Jason Gunthorpe
[not found] ` <20150713201538.GA11681-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2015-07-14 9:10 ` Sagi Grimberg
[not found] ` <55A4D20C.2000904-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-14 15:36 ` 'Christoph Hellwig'
[not found] ` <20150714153619.GC11026-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-14 15:47 ` Tom Talpey
2015-07-14 16:22 ` Jason Gunthorpe
2015-07-14 7:37 ` 'Christoph Hellwig'
2015-07-14 9:22 ` Sagi Grimberg
[not found] ` <55A4D4C6.6040907-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-14 12:12 ` Tom Talpey
2015-07-14 13:23 ` Sagi Grimberg
2015-07-14 14:45 ` Steve Wise
2015-07-14 15:40 ` 'Christoph Hellwig'
2015-07-08 8:11 ` 'Christoph Hellwig'
2015-07-06 7:58 ` Sagi Grimberg
[not found] ` <559A3536.3020807-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2015-07-06 14:39 ` Steve Wise
2015-07-05 23:22 ` [PATCH V3 2/5] RDMA/iser: Use transport independent MR allocation Steve Wise
[not found] ` <20150705231831.12029.80307.stgit-PBeJgSbIpn97NCTnQtmixQ@public.gmane.org>
2015-07-05 23:22 ` [PATCH V3 3/5] RDMA/isert: " Steve Wise
2015-07-05 23:22 ` [PATCH V3 4/5] svcrdma: " Steve Wise
2015-07-05 23:22 ` [PATCH V3 5/5] xprtrdma: " Steve Wise
2015-07-06 5:25 ` [PATCH V3 0/5] Transport-independent MRs Christoph Hellwig
[not found] ` <20150706052542.GB1109-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-07-06 14:24 ` Steve Wise
2015-07-07 9:01 ` 'Christoph Hellwig'
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