RE: Regarding to the recent Intel IAA/DSA/QAT support on migration

[Liu, Yuan1]

Thank you very much for your reminder and the rapid updates to the
multifd function. I will incorporate your suggestions into the next
version (IAA Accelerated Live Migration solution). 

Regarding the QAT and DSA optimization, my colleagues and I have 
already started reviewing and testing them, and it seems like a 
promising optimization direction. I am more than willing to contribute 
further efforts to the long-term maintenance of Intel accelerators in 
live migration.

> -----Original Message-----
> From: Peter Xu <peterx@redhat.com>
> Sent: Wednesday, February 7, 2024 4:10 PM
> To: Bryan Zhang <bryan.zhang@bytedance.com>; Hao Xiang
> <hao.xiang@bytedance.com>; Liu, Yuan1 <yuan1.liu@intel.com>
> Cc: Fabiano Rosas <farosas@suse.de>; QEMU Devel Mailing List <qemu-
> devel@nongnu.org>
> Subject: Regarding to the recent Intel IAA/DSA/QAT support on migration
> 
> Copy qemu-devel.
> 
> On Wed, Feb 07, 2024 at 04:07:40PM +0800, Peter Xu wrote:
> > Hi,
> >
> > I'm sending this email just to leave a generic comment to the recent
> > migration efforts to enable these new Intel technologies.
> >
> > The relevant patchsets (latest version so far) we're discussing are:
> >
> >   [PATCH v3 0/4] Live Migration Acceleration with IAA Compression
> >
> > https://lore.kernel.org/r/20240103112851.908082-1-yuan1.liu@intel.com
> >
> >   [PATCH v3 00/20] Use Intel DSA accelerator to offload zero page
> checking in multifd live migration.
> >
> > https://lore.kernel.org/r/20240104004452.324068-1-hao.xiang@bytedance.
> > com
> >
> >   [PATCH 0/5] *** Implement using Intel QAT to offload ZLIB
> >
> > https://lore.kernel.org/r/20231231205804.2366509-1-bryan.zhang@bytedan
> > ce.com
> >
> > I want to comment in a generic way since this should apply to all
> > these
> > series:
> >
> >   - A heads-up that multifd code is rapidly changing recently, I
> apologize
> >     that you'll need a rebase.  It's just that it's probably much better
> to
> >     do this before anything lands there.
> >
> >     IIUC the good thing is we found that send_prepare() doesn't need to
> be
> >     changed that much, however there's still some change; please refer
> to
> >     the new code (I'll prepare a pull tomorrow to include most of the
> >     changes, and we should have a major thread race fixed too with
> Fabiano
> >     & Avihai's help). I hope this will also provide some kind of
> isolation
> >     to e.g. other works that may touch other areas.  E.g., I hope fixed-
> ram
> >     won't need to conflict much with any of the above series now.
> >
> >   - When posting the new patchset (if there is a plan..), please make
> sure
> >     we have:
> >
> >     - Proper unit tests for the new code (probably mostly software
> >       fallbacks to be tested on the new libraries being introduced; just
> to
> >       make sure the new library code paths can get some torture please).
> >
> >     - Proper documentation for the new code.  Please feel free to start
> >       creating your own .rst file under docs/devel/migration/, we can
> try
> >       to merge them later.  It should help avoid conflictions.  Please
> also
> >       link the new file into index.rst there.
> >
> >       IMHO the document can contain many things, the important ones
> could
> >       start from: who should enable such feature; what one can get from
> >       having it enabled; what is the HW requirement to enable it; how
> >       should one tune the new parameters, and so on... some links to the
> >       technology behinds it would be nice too to be referenced.
> >
> >     - Try to add new code (especially HW/library based) into new file.
> >       I see that QPL & QAT already proposed its own files (multifd-
> pql.c,
> >       multifd-qatzip.c) which is great.
> >
> >       Xiang, please also consider doing so for the DSA based zero page
> >       detection.  It can be called multifd-zero-page.c, for example, and
> >       you can create it when working on the
> >       offload-zero-page-detect-to-multifd patchset already.
> >
> >     - Please provide someone who can potentially maintain this code if
> ever
> >       possible.  Pushing these code upstream is great, but maintaining
> will
> >       also take effort.  It might be impractical this keeps growing for
> >       migration maintainers (currently Fabiano and myself), so we may
> like
> >       to have people covering these areas, especially when the new codes
> >       are not directly relevant to migration framework.
> >
> >       I'd suggest for each of the project we can add an entry in
> >       MAINTAINERS below "Migration" section, adding relevant files (and
> >       these files should exist in both the new section and "Migration").
> I
> >       am not sure whether Bytedance would be able to cover this, or we
> >       should try to find someone from Intel?  If you're willing to add
> >       yourself to maintain such codes, please attach the maintainers
> file
> >       change together with the series.  It will be very much
> appreciated.
> >
> > Thanks,
> >
> > --
> > Peter Xu
> 
> --
> Peter Xu