[v9] Multifd | Patchew

[Qemu-devel] [PATCH v9 00/12] Multifd

Posted by Juan Quintela 6 years, 6 months ago

This series is on top of my migration test series just sent, only reject should be on the test system, though.

On v9 series for you:
- qobject_unref() as requested by dan

Yes he was right, I had a reference leak for _non_ multifd, I
*thought* he mean for multifd, and that took a while to understand
(and then find when/where).

- multifd page count: it is dropped for good
- uuid handling: we use the default qemu uuid of 0000...
- uuid handling: using and struct and sending the struct
* idea is to add a size field and add more parameter after that
* anyone has a good idea how to "ouptut" info
migrate_capabilities/parameters json into a string and how to read it back?
- changed how we test that all threads/channels are already created.
Should be more robust.
- Add tests multifd. Still not ported on top of migration-tests series sent early
waiting for review on the ideas there.
- Rebase and remove al the integrated patches (back at 12)

Please, review.

Later, Juan.

[v8]
Things NOT done yet:

- drop x-multifd-page-count? We can use performance to set a default value
- paolo suggestion of not having a control channel
needs iyet more cleanups to be able to have more than one ramstate, trying it.
- still not performance done, but it has been very stable

On v8:
- use connect_async
- rename multifd-group to multifd-page-count (danp suggestion)
- rename multifd-threads to multifd-channels (danp suggestion)
- use new qio*channel functions
- Address rest of comments left

So, please review.

My idea will be to pull this changes and continue performance changes
for inside, basically everything is already reviewed.

Thanks, Juan.

On v7:
- tests fixed as danp wanted
- have to revert danp qio_*_all patches, as they break multifd, I have to investigate why.
- error_abort is gone. After several tries about getting errors, I ended having a single error
proceted by a lock and first error wins.
- Addressed basically all reviews (see on ToDo)
- Pointers to struct are done now
- fix lots of leaks
- lots of small fixes

[v6]
- Improve migration_ioc_porcess_incoming
- teach about G_SOURCE_REMOVE/CONTINUE
- Add test for migration_has_all_channels
- use DEFIN_PROP*
- change recv_state to use pointers to parameters
make easier to receive channels out of order
- use g_strdup_printf()
- improve count of threads to know when we have to finish
- report channel id's on errors
- Use last_page parameter for multifd_send_page() sooner
- Improve commets for address
- use g_new0() instead of g_malloc()
- create MULTIFD_CONTINUE instead of using UINT16_MAX
- clear memory used by group of pages
once there, pass everything to the global state variables instead of being
local to the function. This way it works if we cancel migration and start
a new one
- Really wait to create the migration_thread until all channels are created
- split initial_bytes setup to make clearer following patches.
- createRAM_SAVE_FLAG_MULTIFD_SYNC macro, to make clear what we are doing
- move setting of need_flush to inside bitmap_sync
- Lots of other small changes & reorderings

Please, comment.

[v5]

- tests from qio functions (a.k.a. make danp happy)
- 1st message from one channel to the other contains:
<uuid> multifd <channel number>
This would allow us to create more channels as we want them.
a.k.a. Making dave happy
- Waiting in reception for new channels using qio listeners
Getting threads, qio and reference counters working at the same time
was interesing.
Another make danp happy.

- Lots and lots of small changes and fixes. Notice that the last 70 patches
that I merged or so what to make this series easier/smaller.

- NOT DONE: I haven't been woring on measuring performance
differences, this was about getting the creation of the
threads/channels right.

So, what I want:

- Are people happy with how I have (ab)used qio channels? (yes danp,
that is you).
- My understanding is th

ToDo:

- Make paolo happy: He wanted to test using control information
through each channel, not only pages. This requires yet more
cleanups to be able to have more than one QEMUFile/RAMState open at
the same time.

- How I create multiple channels. Things I know:
* with current changes, it should work with fd/channels (the multifd bits),
but we don;t have a way to pass multiple fd;s or exec files.
Danp, any idea about how to create an UI for it?
* My idea is that we would split current code to be:
+ channel creation at migration.c
+ rest of bits at ram.c
+ change format to:
<uuid> main <rest of migration capabilities/paramentes> so we can check
<uuid> postcopy <no clue what parameters are needed>
Dave wanted a way to create a new fd for postcopy for some time
+ Adding new channels is easy

- Performance data/numbers: Yes, I wanted to get this out at once, I
would continue with this.

Please, review.

[v4]
This is the 4th version of multifd. Changes:
- XBZRLE don't need to be checked for
- Documentation and defaults are consistent
- split socketArgs
- use iovec instead of creating something similar.
- We use now the exported size of target page (another HACK removal)
- created qio_chanel_{wirtev,readv}_all functions. the _full() name
was already taken.
What they do is the same that the without _all() function, but if it
returns due to blocking it redo the call.
- it is checkpatch.pl clean now.

Please comment, Juan.

Juan Quintela (12):
qapi: Fix grammar in x-multifd-page-count descriptions
migration: Improve migration thread error handling
migration: Make migrate_fd_error() the owner of the Error
migration: Start of multiple fd work
migration: Create ram_multifd_page
migration: Send the fd number which we are going to use for this page
migration: Create thread infrastructure for multifd recv side
migration: Test new fd infrastructure
migration: Rename initial_bytes
migration: Transfer pages over new channels
migration: Flush receive queue
migration: Add multifd test

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