From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: "Marciniszyn,
Mike" <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: "Dalessandro,
Dennis"
<dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
Leon Romanovsky <leon-2ukJVAZIZ/Y@public.gmane.org>,
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH v2 19/20] IB/rdmavt, IB/qib, IB/hfi1: Make percpu refcount optional for user MRs
Date: Thu, 6 Apr 2017 11:44:38 -0600 [thread overview]
Message-ID: <20170406174438.GA20020@obsidianresearch.com> (raw)
In-Reply-To: <32E1700B9017364D9B60AED9960492BC342EADEE-RjuIdWtd+YbTXloPLtfHfbfspsVTdybXVpNB7YpNyf8@public.gmane.org>
On Thu, Apr 06, 2017 at 05:16:31PM +0000, Marciniszyn, Mike wrote:
> > > There were two patches in the patch series, one reworks the rdmavt
> > > read side MR to allow for getting rid of an explicit RCU at deref
> > > time. The second module parameter was intended to allow for a faster
> > > memory registration for user MRs as an option.
> >
> > If it is faster why wouldn't you always just use that mode?
>
> It would be faster mr deregistration, but slower data patch since
> atomic operations would then be done.
Umm.. This doesn't look like a refcount, it is a rwlock - why aren't
you using the optimized percpu_rwsem?
Seriously, making a rwlock out of a completion and a percpu_refcount
and then providing user options to micro-optimize it is fantastically
ugly/bad taste.
Jason
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next prev parent reply other threads:[~2017-04-06 17:44 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-21 0:24 [PATCH v2 00/20] IB/hfi1, qib, rdmavt: Another round of patches for 4.11 Dennis Dalessandro
2017-03-21 0:24 ` Dennis Dalessandro
[not found] ` <20170321001900.28538.38175.stgit-9QXIwq+3FY+1XWohqUldA0EOCMrvLtNR@public.gmane.org>
2017-03-21 0:24 ` [PATCH v2 01/20] IB/hfi1: Force logical link down Dennis Dalessandro
2017-03-21 0:24 ` [PATCH v2 02/20] IB/hfi1: Race hazard avoidance in user SDMA driver Dennis Dalessandro
2017-03-21 0:24 ` [PATCH v2 03/20] IB/hfi1: Cache registers during state change Dennis Dalessandro
2017-03-21 0:24 ` [PATCH v2 04/20] IB/hfi1: NULL pointer dereference when freeing rhashtable Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 05/20] IB/rdmavt, IB/hfi1, IB/qib: Make wc opcode translation driver dependent Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 06/20] IB/rdmavt: Add additional fields to post send trace Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 07/20] IB/rdmavt: Add tracing for cq entry and poll Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 08/20] IB/rdmavt: Add swqe completion trace Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 09/20] IB/hfi1: Check device id early during init Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 10/20] IB/hfi1: Protect the global dev_cntr_names and port_cntr_names Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 11/20] IB/hfi1: Check for QSFP presence before attempting reads Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 12/20] IB/hfi1: Add a patch value to the firmware version string Dennis Dalessandro
2017-03-21 0:25 ` [PATCH v2 13/20] IB/rdmavt, IB/hfi1: Fix timer migration regressions Dennis Dalessandro
2017-03-21 0:26 ` [PATCH v2 14/20] IB/rdmavt: Avoid reseting wqe send_flags in unreserve Dennis Dalessandro
2017-03-21 0:26 ` [PATCH v2 15/20] IB/hfi1: Ensure VL index is within bounds Dennis Dalessandro
2017-03-21 0:26 ` [PATCH v2 16/20] IB/hfi1: Add receive fault injection feature Dennis Dalessandro
2017-03-21 0:26 ` [PATCH v2 17/20] IB/hfi1: Add transmit " Dennis Dalessandro
[not found] ` <20170321002619.28538.31428.stgit-9QXIwq+3FY+1XWohqUldA0EOCMrvLtNR@public.gmane.org>
2017-04-05 18:34 ` Doug Ledford
[not found] ` <1491417255.2923.5.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-04-05 18:49 ` Dennis Dalessandro
2017-03-21 0:26 ` [PATCH v2 18/20] IB/hfi1: Eliminate synchronize_rcu() in mr delete Dennis Dalessandro
2017-03-21 0:26 ` [PATCH v2 19/20] IB/rdmavt, IB/qib, IB/hfi1: Make percpu refcount optional for user MRs Dennis Dalessandro
[not found] ` <20170321002631.28538.2121.stgit-9QXIwq+3FY+1XWohqUldA0EOCMrvLtNR@public.gmane.org>
2017-04-05 18:38 ` Doug Ledford
[not found] ` <1491417489.2923.6.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-04-05 19:46 ` Dennis Dalessandro
[not found] ` <f008c532-340e-01f2-80e6-4bea74175e3e-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2017-04-05 19:51 ` Leon Romanovsky
[not found] ` <CALq1K=JsjSCiSBeZVe4kHQmjw7tznL36JcsamZTVGZ5RhBvZPw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-05 20:09 ` Marciniszyn, Mike
[not found] ` <32E1700B9017364D9B60AED9960492BC342EA858-RjuIdWtd+YbTXloPLtfHfbfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2017-04-06 7:49 ` Leon Romanovsky
[not found] ` <20170406074955.GG2269-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-04-06 11:45 ` Dennis Dalessandro
[not found] ` <8cdf2fbb-f2a9-0b4b-b144-397ee73d1569-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2017-04-06 12:37 ` Leon Romanovsky
[not found] ` <20170406123726.GH2269-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-04-06 13:00 ` Dennis Dalessandro
[not found] ` <f1703866-9c5c-a30a-0d95-9f6a33cc4f75-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2017-04-06 13:33 ` Leon Romanovsky
2017-04-06 14:47 ` Marciniszyn, Mike
[not found] ` <32E1700B9017364D9B60AED9960492BC342EABD0-RjuIdWtd+YbTXloPLtfHfbfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2017-04-06 17:13 ` Jason Gunthorpe
[not found] ` <20170406171354.GA19854-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-04-06 17:16 ` Marciniszyn, Mike
[not found] ` <32E1700B9017364D9B60AED9960492BC342EADEE-RjuIdWtd+YbTXloPLtfHfbfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2017-04-06 17:44 ` Jason Gunthorpe [this message]
[not found] ` <20170406174438.GA20020-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-04-07 21:12 ` Marciniszyn, Mike
[not found] ` <32E1700B9017364D9B60AED9960492BC342EBA18-RjuIdWtd+YbTXloPLtfHfbfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2017-04-07 22:06 ` Jason Gunthorpe
[not found] ` <20170407220618.GA29138-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-04-09 6:26 ` Leon Romanovsky
2017-04-05 19:47 ` Leon Romanovsky
2017-03-21 0:26 ` [PATCH v2 20/20] IB/core: If the MGID/MLID pair is not on the list return an error Dennis Dalessandro
2017-04-05 18:50 ` [PATCH v2 00/20] IB/hfi1, qib, rdmavt: Another round of patches for 4.11 Doug Ledford
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