From: Peter Xu <peterx@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
"Zengtao (B)" <prime.zeng@hisilicon.com>,
Cornelia Huck <cohuck@redhat.com>,
Kevin Tian <kevin.tian@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
Michel Lespinasse <walken@google.com>,
Jann Horn <jannh@google.com>, Max Gurtovoy <mgurtovoy@nvidia.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linuxarm <linuxarm@huawei.com>
Subject: Re: [PATCH] vfio/pci: make the vfio_pci_mmap_fault reentrant
Date: Tue, 9 Mar 2021 16:00:36 -0500 [thread overview]
Message-ID: <20210309210036.GJ763132@xz-x1> (raw)
In-Reply-To: <20210309131104.1094b798@omen.home.shazbot.org>
On Tue, Mar 09, 2021 at 01:11:04PM -0700, Alex Williamson wrote:
> > It's just that the initial MMIO access delay would be spread to the 1st access
> > of each mmio page access rather than using the previous pre-fault scheme. I
> > think an userspace cares the delay enough should pre-fault all pages anyway,
> > but just raise this up. Otherwise looks sane.
>
> Yep, this is a concern. Is it safe to have loops concurrently and fully
> populating the same vma with vmf_insert_pfn()?
AFAIU it's safe, and probably the (so far) best way for an userspace to quickly
populate a huge chunk of mmap()ed region for either MMIO or RAM. Indeed from
that pov vmf_insert_pfn() seems to be even more efficient on prefaulting since
it can be threaded.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-03-09 21:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-08 11:11 Zeng Tao
2021-03-08 20:21 ` Alex Williamson
2021-03-08 22:56 ` Peter Xu
2021-03-09 3:49 ` 答复: " Zengtao (B)
2021-03-09 12:46 ` Jason Gunthorpe
2021-03-09 15:29 ` Alex Williamson
2021-03-09 16:40 ` Jason Gunthorpe
2021-03-09 18:47 ` Peter Xu
2021-03-09 19:26 ` Alex Williamson
2021-03-09 19:48 ` Peter Xu
2021-03-09 20:11 ` Alex Williamson
2021-03-09 21:00 ` Peter Xu [this message]
2021-03-09 21:43 ` Alex Williamson
2021-03-09 19:56 ` Alex Williamson
2021-03-09 23:45 ` Jason Gunthorpe
2021-03-10 6:23 ` Alex Williamson
2021-03-09 23:41 ` Jason Gunthorpe
2021-03-10 6:08 ` Alex Williamson
2021-03-11 3:32 ` 答复: " Zengtao (B)
2021-03-08 23:43 ` Jason Gunthorpe
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