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From: Peter Xu <peterx@redhat.com>
To: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>
Cc: Juan Quintela <quintela@redhat.com>,
	Markus Armbruster <armbru@redhat.com>,
	qemu-devel@nongnu.org,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>, Den Lunev <den@openvz.org>
Subject: Re: [PATCH v4 0/6] UFFD write-tracking migration/snapshots
Date: Fri, 27 Nov 2020 17:04:16 -0500	[thread overview]
Message-ID: <20201127220416.GH6573@xz-x1> (raw)
In-Reply-To: <20201126151734.743849-1-andrey.gruzdev@virtuozzo.com>

On Thu, Nov 26, 2020 at 06:17:28PM +0300, Andrey Gruzdev wrote:
> Changes v3->v4:
> 
> * 1. Renamed migrate capability 'track-writes-ram'->'background-snapshot'.
> * 2. Use array of incompatible caps to replace bulky 'if' constructs.
> * 3. Moved UFFD low-level code to the separate module ('util/userfaultfd.c').
> * 4. Always do UFFD wr-unprotect on cleanup; just closing file descriptor
> *    won't cleanup PTEs anyhow, it will release registration ranges, wait 
> *    queues etc. but won't cleanup process MM context on MMU level.
> * 5. Allow to enable 'background-snapshot' capability on Linux-only hosts.
> * 6. Put UFFD code usage under '#ifdef CONFIG_LINUX' prerequisite.
> * 7. Removed 'wt_' from RAMState struct.
> * 8. Refactored ram_find_and_save_block() to make more clean - poll UFFD
> *    wr-fault events in get_queued_page(), use ram_save_host_page_pre(),
> *    ram_save_host_page_post() notifiers around ram_save_host_page()
> *    instead of bulky inline write-unprotect code.

One thing I mentioned previously but it seems still got lost is that we don't
need dirty tracking for live snapshot.

A few pointers for reference:

  memory_global_dirty_log_start()
  migration_bitmap_sync_precopy()
  memory_region_clear_dirty_bitmap()
  ...

These should not be needed.  But this can also be done on top.

Thanks,

-- 
Peter Xu



  parent reply	other threads:[~2020-11-27 22:05 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-26 15:17 [PATCH v4 0/6] UFFD write-tracking migration/snapshots Andrey Gruzdev via
2020-11-26 15:17 ` [PATCH v4 1/6] introduce 'background-snapshot' migration capability Andrey Gruzdev via
2020-11-27 19:55   ` Peter Xu
2020-11-28 16:35     ` Andrey Gruzdev
2020-11-26 15:17 ` [PATCH v4 2/6] introduce UFFD-WP low-level interface helpers Andrey Gruzdev via
2020-11-27 21:04   ` Peter Xu
2020-11-29 20:12     ` Andrey Gruzdev
2020-11-30 15:34       ` Peter Xu
2020-11-30 18:41         ` Andrey Gruzdev
2020-12-01 12:24   ` Dr. David Alan Gilbert
2020-12-01 19:32     ` Andrey Gruzdev
2020-11-26 15:17 ` [PATCH v4 3/6] support UFFD write fault processing in ram_save_iterate() Andrey Gruzdev via
2020-11-27 21:49   ` Peter Xu
2020-11-29 21:14     ` Andrey Gruzdev
2020-11-30 16:32       ` Peter Xu
2020-11-30 19:27         ` Andrey Gruzdev
2020-11-26 15:17 ` [PATCH v4 4/6] implementation of background snapshot thread Andrey Gruzdev via
2020-11-26 15:17 ` [PATCH v4 5/6] the rest of write tracking migration code Andrey Gruzdev via
2020-11-27 22:26   ` Peter Xu
2020-11-30  8:09     ` Andrey Gruzdev
2020-11-26 15:17 ` [PATCH v4 6/6] introduce simple linear scan rate limiting mechanism Andrey Gruzdev via
2020-11-27 22:28   ` Peter Xu
2020-11-30  8:11     ` Andrey Gruzdev
2020-11-30 16:40       ` Peter Xu
2020-11-30 19:30         ` Andrey Gruzdev
2020-11-26 15:47 ` [PATCH v4 0/6] UFFD write-tracking migration/snapshots Peter Krempa
2020-11-27  8:21   ` Andrey Gruzdev
2020-11-27  9:49     ` Peter Krempa
2020-11-27 10:00       ` Andrey Gruzdev
2020-11-27 15:45         ` Peter Xu
2020-11-27 17:19           ` Andrey Gruzdev
2020-11-27 22:04 ` Peter Xu [this message]
2020-11-30  8:07   ` Andrey Gruzdev
2020-12-01  7:08 ` Peter Krempa
2020-12-01  8:42   ` Andrey Gruzdev
2020-12-01 10:53     ` Peter Krempa
2020-12-01 11:24       ` Andrey Gruzdev
2020-12-01 18:40         ` Dr. David Alan Gilbert
2020-12-01 19:22           ` Peter Xu
2020-12-01 20:01             ` Dr. David Alan Gilbert
2020-12-01 20:29               ` Andrey Gruzdev
2020-12-01 20:11           ` Andrey Gruzdev
2020-12-01 18:54         ` Peter Xu
2020-12-01 20:00           ` Dr. David Alan Gilbert
2020-12-01 20:26           ` Andrey Gruzdev

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