From: "Michael S. Tsirkin" <mst@redhat.com>
To: peter.maydell@linaro.org, yu.c.zhang@linux.intel.com,
ehabkost@redhat.com, imammedo@redhat.com, qemu-devel@nongnu.org,
pbonzini@redhat.com, stefanha@redhat.com,
crosthwaite.peter@gmail.com, richard.henderson@linaro.org,
xiaoguangrong.eric@gmail.com
Subject: Re: [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option
Date: Wed, 19 Dec 2018 10:59:10 -0500 [thread overview]
Message-ID: <20181219105555-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20181219091017.GA35378@tiger-server>
On Wed, Dec 19, 2018 at 05:10:18PM +0800, Yi Zhang wrote:
> > > +
> > > + - 'sync' option of memory-backend-file is not 'off', and
> > > +
> > > + - 'share' option of memory-backend-file is 'on'.
> > > +
> > > + - 'pmem' option of memory-backend-file is 'on'
> > > +
> >
> > Wait isn't this what pmem was supposed to do?
> > Doesn't it mean "persistent memory"?
> pmem is a option for memory-backend-file, user should know the backend
> is in host persistent memory, with this flags on, while there is a host crash
> or a power failures.
>
> [1] Qemu will take necessary operations to guarantee the persistence.
> https://patchwork.ozlabs.org/cover/944749/
>
> [2] Host kernel also take opretions to consistent filesystem metadata.
> Add MAP_SYNC flags.
OK so I'm a user. Can you educate me please? When should MAP_SYNC not
be set? Are there any disadvantages (e.g. performance?)?
--
MST
next prev parent reply other threads:[~2018-12-19 15:59 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-18 8:16 [Qemu-devel] [PATCH V7 0/6] nvdimm: support MAP_SYNC for memory-backend-file Zhang Yi
2018-12-18 8:16 ` [Qemu-devel] [PATCH V7 1/6] numa: Fixed the memory leak of numa error message Zhang Yi
2018-12-18 8:17 ` [Qemu-devel] [PATCH V7 2/6] util/mmap-alloc: switch qemu_ram_mmap() to 'flags' parameter Zhang Yi
2018-12-18 13:35 ` Michael S. Tsirkin
2018-12-18 8:17 ` [Qemu-devel] [PATCH V7 3/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap() Zhang Yi
2018-12-18 13:52 ` Michael S. Tsirkin
2018-12-19 9:25 ` Yi Zhang
2018-12-19 16:42 ` Michael S. Tsirkin
2018-12-18 8:17 ` [Qemu-devel] [PATCH V7 4/6] util/mmap-alloc: Switch the RAM_SYNC flags to OnOffAuto Zhang Yi
2018-12-18 8:17 ` [Qemu-devel] [PATCH V7 5/6] hostmem: add more information in error messages Zhang Yi
2018-12-18 8:17 ` [Qemu-devel] [PATCH V7 6/6] hostmem-file: add 'sync' option Zhang Yi
2018-12-18 14:18 ` Michael S. Tsirkin
2018-12-19 9:10 ` Yi Zhang
2018-12-19 15:59 ` Michael S. Tsirkin [this message]
2018-12-20 3:03 ` Yi Zhang
2018-12-20 3:42 ` Michael S. Tsirkin
2018-12-20 5:37 ` Yi Zhang
2018-12-20 14:06 ` Michael S. Tsirkin
2018-12-21 3:18 ` Yi Zhang
2018-12-21 16:36 ` Michael S. Tsirkin
2018-12-24 8:11 ` Yi Zhang
2019-09-16 15:14 ` Michael S. Tsirkin
2018-12-18 9:18 ` [Qemu-devel] [PATCH V7 0/6] nvdimm: support MAP_SYNC for memory-backend-file Stefan Hajnoczi
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