migration/multifd: solve zero page causing multiple page faults

Implemented recvbitmap tracking of received pages in multifd.

If the zero page appears for the first time in the recvbitmap, this
pag

migration/multifd: solve zero page causing multiple page faults

Implemented recvbitmap tracking of received pages in multifd.

If the zero page appears for the first time in the recvbitmap, this
page is not checked and set.

If the zero page has already appeared in the recvbitmap, there is no
need to check the data but directly set the data to 0, because it is
unlikely that the zero page will be migrated multiple times.

Signed-off-by: Yuan Liu <yuan1.liu@intel.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240401154110.2028453-2-yuan1.liu@intel.com
[peterx: touch up the comment, as the bitmap is used outside postcopy now]
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

migration/multifd: solve zero page causing multiple page faults

Implemented recvbitmap tracking of received pages in multifd.

If the zero page appears for the first time in the recvbitmap, this
pag

migration/multifd: solve zero page causing multiple page faults

Implemented recvbitmap tracking of received pages in multifd.

If the zero page appears for the first time in the recvbitmap, this
page is not checked and set.

If the zero page has already appeared in the recvbitmap, there is no
need to check the data but directly set the data to 0, because it is
unlikely that the zero page will be migrated multiple times.

Signed-off-by: Yuan Liu <yuan1.liu@intel.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240401154110.2028453-2-yuan1.liu@intel.com
[peterx: touch up the comment, as the bitmap is used outside postcopy now]
Signed-off-by: Peter Xu <peterx@redhat.com>

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migration/multifd: Implement zero page transmission on the multifd thread.

1. Add zero_pages field in MultiFDPacket_t.
2. Implements the zero page detection and handling on the multifd
threads for n

migration/multifd: Implement zero page transmission on the multifd thread.

1. Add zero_pages field in MultiFDPacket_t.
2. Implements the zero page detection and handling on the multifd
threads for non-compression, zlib and zstd compression backends.
3. Added a new value 'multifd' in ZeroPageDetection enumeration.
4. Adds zero page counters and updates multifd send/receive tracing
format to track the newly added counters.

Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240311180015.3359271-5-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>

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migration/multifd: Implement zero page transmission on the multifd thread.

1. Add zero_pages field in MultiFDPacket_t.
2. Implements the zero page detection and handling on the multifd
threads for n

migration/multifd: Implement zero page transmission on the multifd thread.

1. Add zero_pages field in MultiFDPacket_t.
2. Implements the zero page detection and handling on the multifd
threads for non-compression, zlib and zstd compression backends.
3. Added a new value 'multifd' in ZeroPageDetection enumeration.
4. Adds zero page counters and updates multifd send/receive tracing
format to track the newly added counters.

Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240311180015.3359271-5-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

migration/multifd: Implement zero page transmission on the multifd thread.

1. Add zero_pages field in MultiFDPacket_t.
2. Implements the zero page detection and handling on the multifd
threads for n

migration/multifd: Implement zero page transmission on the multifd thread.

1. Add zero_pages field in MultiFDPacket_t.
2. Implements the zero page detection and handling on the multifd
threads for non-compression, zlib and zstd compression backends.
3. Added a new value 'multifd' in ZeroPageDetection enumeration.
4. Adds zero page counters and updates multifd send/receive tracing
format to track the newly added counters.

Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240311180015.3359271-5-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>

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migration/multifd: Decouple recv method from pages

Next patches will abstract the type of data being received by the
channels, so do some cleanup now to remove references to pages and
dependency on

migration/multifd: Decouple recv method from pages

Next patches will abstract the type of data being received by the
channels, so do some cleanup now to remove references to pages and
dependency on 'normal_num'.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-14-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>

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migration/multifd: Rename MultiFDSend|RecvParams::data to compress_data

Use a more specific name for the compression data so we can use the
generic for the multifd core code.

Reviewed-by: Peter Xu

migration/multifd: Rename MultiFDSend|RecvParams::data to compress_data

Use a more specific name for the compression data so we can use the
generic for the multifd core code.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-13-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>

show more ...

migration/multifd: Decouple recv method from pages

Next patches will abstract the type of data being received by the
channels, so do some cleanup now to remove references to pages and
dependency on

migration/multifd: Decouple recv method from pages

Next patches will abstract the type of data being received by the
channels, so do some cleanup now to remove references to pages and
dependency on 'normal_num'.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-14-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>

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migration/multifd: Rename MultiFDSend|RecvParams::data to compress_data

Use a more specific name for the compression data so we can use the
generic for the multifd core code.

Reviewed-by: Peter Xu

migration/multifd: Rename MultiFDSend|RecvParams::data to compress_data

Use a more specific name for the compression data so we can use the
generic for the multifd core code.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-13-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>

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migration/multifd: Move header prepare/fill into send_prepare()

This patch redefines the interfacing of ->send_prepare(). It further
simplifies multifd_send_thread() especially on zero copy.

Now w

migration/multifd: Move header prepare/fill into send_prepare()

This patch redefines the interfacing of ->send_prepare(). It further
simplifies multifd_send_thread() especially on zero copy.

Now with the new interface, we require the hook to do all the work for
preparing the IOVs to send. After it's completed, the IOVs should be ready
to be dumped into the specific multifd QIOChannel later.

So now the API looks like:

p->pages -----------> send_prepare() -------------> IOVs

This also prepares for the case where the input can be extended to even not
any p->pages. But that's for later.

This patch will achieve similar goal of what Fabiano used to propose here:

https://lore.kernel.org/r/20240126221943.26628-1-farosas@suse.de

However the send() interface may not be necessary. I'm boldly attaching a
"Co-developed-by" for Fabiano.

Co-developed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240202102857.110210-14-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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migration/multifd: Drop MultiFDSendParams.normal[] array

This array is redundant when p->pages exists. Now we extended the life of
p->pages to the whole period where pending_job is set, it should b

migration/multifd: Drop MultiFDSendParams.normal[] array

This array is redundant when p->pages exists. Now we extended the life of
p->pages to the whole period where pending_job is set, it should be safe to
always use p->pages->offset[] rather than p->normal[]. Drop the array.

Alongside, the normal_num is also redundant, which is the same to
p->pages->num.

This doesn't apply to recv side, because there's no extra buffering on recv
side, so p->normal[] array is still needed.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240202102857.110210-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

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migration: spelling fixes

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Fabiano Rosas <farosas@suse.de>

migration: spelling fixes

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Fabiano Rosas <farosas@suse.de>

migration: spelling fixes

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Fabiano Rosas <farosas@suse.de>

migration: Move parameters functions to option.c

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

migration: Move parameters functions to option.c

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

migration: Move parameters functions to option.c

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

migration: Move parameters functions to option.c

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

multifd: Create page_size fields into both MultiFD{Recv,Send}Params

We were calling qemu_target_page_size() left and right.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo

multifd: Create page_size fields into both MultiFD{Recv,Send}Params

We were calling qemu_target_page_size() left and right.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo Bras <leobras@redhat.com>

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multifd: Create page_size fields into both MultiFD{Recv,Send}Params

We were calling qemu_target_page_size() left and right.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo

multifd: Create page_size fields into both MultiFD{Recv,Send}Params

We were calling qemu_target_page_size() left and right.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo Bras <leobras@redhat.com>

show more ...

multifd: Create page_size fields into both MultiFD{Recv,Send}Params

We were calling qemu_target_page_size() left and right.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo

multifd: Create page_size fields into both MultiFD{Recv,Send}Params

We were calling qemu_target_page_size() left and right.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo Bras <leobras@redhat.com>

show more ...

multifd: recv side only needs the RAMBlock host address

So we can remove the MultiFDPages.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.co

multifd: recv side only needs the RAMBlock host address

So we can remove the MultiFDPages.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

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multifd: Use normal pages array on the recv side

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

---

Rename num_normal_pages to total_n

multifd: Use normal pages array on the recv side

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

---

Rename num_normal_pages to total_normal_pages (peter)

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multifd: Use normal pages array on the send side

We are only sending normal pages through multifd channels.
Later on this series, we are going to also send zero pages.
We are going to detect if a pa

multifd: Use normal pages array on the send side

We are only sending normal pages through multifd channels.
Later on this series, we are going to also send zero pages.
We are going to detect if a page is zero or non zero in the multifd
channel thread, not on the main thread.

So we receive an array of pages page->offset[N]

And we will end with:

p->normal[N - zero_pages]
p->zero[zero_pages].

In this patch, we just copy all the pages in offset to normal.

for (i = 0; i < pages->num; i++) {
p->narmal[p->normal_num] = pages->offset[i];
p->normal_num++:
}

Later in the series this becomes:

for (i = 0; i < pages->num; i++) {
if (buffer_is_zero(page->offset[i])) {
p->zerol[p->zero_num] = pages->offset[i];
p->zero_num++:
} else {
p->narmal[p->normal_num] = pages->offset[i];
p->normal_num++:
}
}

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

---

Improving comment (dave)
Renaming num_normal_pages to total_normal_pages (peter)

show more ...

multifd: Remove send_write() method

Everything use now iov's.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>