From: Roland Dreier <roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: "Michael S. Tsirkin" <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: "Michael R. Hines"
<mrhines-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
Hal Rosenstock
<hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Yishai Hadas <yishaih-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>,
"linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org
Subject: Re: [PATCH] rdma: don't make pages writeable if not requiested
Date: Thu, 21 Mar 2013 02:13:38 -0700 [thread overview]
Message-ID: <CAL1RGDVnkLZU2Vge4o3BwDxnAfGv7TQRMqE6ha3MUt39CVp5NQ@mail.gmail.com> (raw)
In-Reply-To: <20130321085107.GE28328-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
On Thu, Mar 21, 2013 at 1:51 AM, Michael S. Tsirkin <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
>> In that case, no, I don't see any reason for LOCAL_WRITE, since the
>> only RDMA operations that will access this memory are remote reads.
>
> What is the meaning of LOCAL_WRITE then? There are no local
> RDMA writes as far as I can see.
Umm, it means you're giving the local adapter permission to write to
that memory. So you can use it as a receive buffer or as the target
for remote data from an RDMA read operation.
> OK then what we need is a new flag saying "I really do not
> intend to write into this memory please do not break
> COW or do anything else just in case I do".
Isn't that a shared read-only mapping?
- R.
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WARNING: multiple messages have this Message-ID (diff)
From: Roland Dreier <roland@kernel.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Michael R. Hines" <mrhines@linux.vnet.ibm.com>,
Sean Hefty <sean.hefty@intel.com>,
Hal Rosenstock <hal.rosenstock@gmail.com>,
Yishai Hadas <yishaih@mellanox.com>,
Christoph Lameter <cl@linux.com>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
qemu-devel@nongnu.org
Subject: Re: [PATCH] rdma: don't make pages writeable if not requiested
Date: Thu, 21 Mar 2013 02:13:38 -0700 [thread overview]
Message-ID: <CAL1RGDVnkLZU2Vge4o3BwDxnAfGv7TQRMqE6ha3MUt39CVp5NQ@mail.gmail.com> (raw)
In-Reply-To: <20130321085107.GE28328@redhat.com>
On Thu, Mar 21, 2013 at 1:51 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
>> In that case, no, I don't see any reason for LOCAL_WRITE, since the
>> only RDMA operations that will access this memory are remote reads.
>
> What is the meaning of LOCAL_WRITE then? There are no local
> RDMA writes as far as I can see.
Umm, it means you're giving the local adapter permission to write to
that memory. So you can use it as a receive buffer or as the target
for remote data from an RDMA read operation.
> OK then what we need is a new flag saying "I really do not
> intend to write into this memory please do not break
> COW or do anything else just in case I do".
Isn't that a shared read-only mapping?
- R.
WARNING: multiple messages have this Message-ID (diff)
From: Roland Dreier <roland@kernel.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: qemu-devel@nongnu.org,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
Yishai Hadas <yishaih@mellanox.com>,
LKML <linux-kernel@vger.kernel.org>,
"Michael R. Hines" <mrhines@linux.vnet.ibm.com>,
Hal Rosenstock <hal.rosenstock@gmail.com>,
Sean Hefty <sean.hefty@intel.com>,
Christoph Lameter <cl@linux.com>
Subject: Re: [Qemu-devel] [PATCH] rdma: don't make pages writeable if not requiested
Date: Thu, 21 Mar 2013 02:13:38 -0700 [thread overview]
Message-ID: <CAL1RGDVnkLZU2Vge4o3BwDxnAfGv7TQRMqE6ha3MUt39CVp5NQ@mail.gmail.com> (raw)
In-Reply-To: <20130321085107.GE28328@redhat.com>
On Thu, Mar 21, 2013 at 1:51 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
>> In that case, no, I don't see any reason for LOCAL_WRITE, since the
>> only RDMA operations that will access this memory are remote reads.
>
> What is the meaning of LOCAL_WRITE then? There are no local
> RDMA writes as far as I can see.
Umm, it means you're giving the local adapter permission to write to
that memory. So you can use it as a receive buffer or as the target
for remote data from an RDMA read operation.
> OK then what we need is a new flag saying "I really do not
> intend to write into this memory please do not break
> COW or do anything else just in case I do".
Isn't that a shared read-only mapping?
- R.
next prev parent reply other threads:[~2013-03-21 9:13 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-21 6:18 [PATCH] rdma: don't make pages writeable if not requiested Michael S. Tsirkin
2013-03-21 6:18 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 6:18 ` Michael S. Tsirkin
[not found] ` <20130321061838.GA28319-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 6:55 ` Roland Dreier
2013-03-21 6:55 ` [Qemu-devel] " Roland Dreier
2013-03-21 6:55 ` Roland Dreier
[not found] ` <CAL1RGDUcMj9QVsuQgK+ozw64L6-cGehL7YBUJ1_ckni6TD=Kcg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-03-21 7:03 ` Michael S. Tsirkin
2013-03-21 7:03 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 7:03 ` Michael S. Tsirkin
[not found] ` <20130321070357.GD28328-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 7:15 ` Roland Dreier
2013-03-21 7:15 ` [Qemu-devel] " Roland Dreier
2013-03-21 7:15 ` Roland Dreier
[not found] ` <CAG4TOxPkhOhGmzeA1K4a0Zw8HxS-QkOr-PCx7mJgA+KkuH3ZiQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-03-21 8:51 ` Michael S. Tsirkin
2013-03-21 8:51 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 8:51 ` Michael S. Tsirkin
[not found] ` <20130321085107.GE28328-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 9:13 ` Roland Dreier [this message]
2013-03-21 9:13 ` [Qemu-devel] " Roland Dreier
2013-03-21 9:13 ` Roland Dreier
[not found] ` <CAL1RGDVnkLZU2Vge4o3BwDxnAfGv7TQRMqE6ha3MUt39CVp5NQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-03-21 9:39 ` Michael S. Tsirkin
2013-03-21 9:39 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 9:39 ` Michael S. Tsirkin
[not found] ` <20130321093946.GG28328-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 17:11 ` Jason Gunthorpe
2013-03-21 17:11 ` [Qemu-devel] " Jason Gunthorpe
2013-03-21 17:11 ` Jason Gunthorpe
[not found] ` <20130321171115.GA653-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2013-03-21 17:15 ` Michael S. Tsirkin
2013-03-21 17:15 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 17:15 ` Michael S. Tsirkin
[not found] ` <20130321171525.GE2994-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 17:21 ` Jason Gunthorpe
2013-03-21 17:21 ` [Qemu-devel] " Jason Gunthorpe
2013-03-21 17:21 ` Jason Gunthorpe
[not found] ` <20130321172150.GA3118-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2013-03-21 17:42 ` Michael S. Tsirkin
2013-03-21 17:42 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 17:42 ` Michael S. Tsirkin
[not found] ` <20130321174237.GA4060-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 17:57 ` Jason Gunthorpe
2013-03-21 17:57 ` [Qemu-devel] " Jason Gunthorpe
2013-03-21 17:57 ` Jason Gunthorpe
[not found] ` <20130321175732.GA3263-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2013-03-21 18:03 ` Michael S. Tsirkin
2013-03-21 18:03 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 18:03 ` Michael S. Tsirkin
2013-03-21 18:16 ` Michael S. Tsirkin
2013-03-21 18:16 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 18:16 ` Michael S. Tsirkin
[not found] ` <20130321181633.GC4366-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 18:41 ` Jason Gunthorpe
2013-03-21 18:41 ` [Qemu-devel] " Jason Gunthorpe
2013-03-21 18:41 ` Jason Gunthorpe
[not found] ` <20130321184135.GA8044-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2013-03-21 19:15 ` Michael S. Tsirkin
2013-03-21 19:15 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 19:15 ` Michael S. Tsirkin
[not found] ` <20130321191541.GB5272-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 20:09 ` Jason Gunthorpe
2013-03-21 20:09 ` [Qemu-devel] " Jason Gunthorpe
2013-03-21 20:09 ` Jason Gunthorpe
2013-03-21 9:32 ` Michael S. Tsirkin
2013-03-21 9:32 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 9:32 ` Michael S. Tsirkin
[not found] ` <20130321093230.GF28328-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-03-21 11:30 ` Michael S. Tsirkin
2013-03-21 11:30 ` [Qemu-devel] " Michael S. Tsirkin
2013-03-21 11:30 ` Michael S. Tsirkin
2013-03-21 12:23 ` Michael R. Hines
2013-03-21 12:23 ` [Qemu-devel] " Michael R. Hines
2013-03-21 12:23 ` Michael R. Hines
2013-03-21 12:32 ` Michael S. Tsirkin
2013-03-21 12:32 ` [Qemu-devel] " Michael S. Tsirkin
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