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From: Peter Xu <peterx@redhat.com>
To: qemu-devel@nongnu.org
Cc: Juraj Marcin <jmarcin@redhat.com>,
	peterx@redhat.com, Fabiano Rosas <farosas@suse.de>,
	"Dr . David Alan Gilbert" <dave@treblig.org>
Subject: [PATCH 03/11] migration/docs: Move docs for postcopy blocktime feature
Date: Tue, 27 May 2025 17:58:42 -0400	[thread overview]
Message-ID: <20250527215850.1271072-4-peterx@redhat.com> (raw)
In-Reply-To: <20250527215850.1271072-1-peterx@redhat.com>

Move it out of vanilla postcopy session, but instead a standalone feature.
When at it, removing the NOTE because it's incorrect now after introduction
of max-postcopy-bandwidth, which can control the throughput even for
postcopy phase.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 docs/devel/migration/postcopy.rst | 36 +++++++++++++++----------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/docs/devel/migration/postcopy.rst b/docs/devel/migration/postcopy.rst
index 82e7a848c6..e319388d8f 100644
--- a/docs/devel/migration/postcopy.rst
+++ b/docs/devel/migration/postcopy.rst
@@ -33,25 +33,6 @@ will now cause the transition from precopy to postcopy.
 It can be issued immediately after migration is started or any
 time later on.  Issuing it after the end of a migration is harmless.
 
-Blocktime is a postcopy live migration metric, intended to show how
-long the vCPU was in state of interruptible sleep due to pagefault.
-That metric is calculated both for all vCPUs as overlapped value, and
-separately for each vCPU. These values are calculated on destination
-side.  To enable postcopy blocktime calculation, enter following
-command on destination monitor:
-
-``migrate_set_capability postcopy-blocktime on``
-
-Postcopy blocktime can be retrieved by query-migrate qmp command.
-postcopy-blocktime value of qmp command will show overlapped blocking
-time for all vCPU, postcopy-vcpu-blocktime will show list of blocking
-time per vCPU.
-
-.. note::
-  During the postcopy phase, the bandwidth limits set using
-  ``migrate_set_parameter`` is ignored (to avoid delaying requested pages that
-  the destination is waiting for).
-
 Postcopy internals
 ==================
 
@@ -312,3 +293,20 @@ explicitly) to be sent in a separate preempt channel, rather than queued in
 the background migration channel.  Anyone who cares about latencies of page
 faults during a postcopy migration should enable this feature.  By default,
 it's not enabled.
+
+Postcopy blocktime statistics
+-----------------------------
+
+Blocktime is a postcopy live migration metric, intended to show how
+long the vCPU was in state of interruptible sleep due to pagefault.
+That metric is calculated both for all vCPUs as overlapped value, and
+separately for each vCPU. These values are calculated on destination
+side.  To enable postcopy blocktime calculation, enter following
+command on destination monitor:
+
+``migrate_set_capability postcopy-blocktime on``
+
+Postcopy blocktime can be retrieved by query-migrate qmp command.
+postcopy-blocktime value of qmp command will show overlapped blocking
+time for all vCPU, postcopy-vcpu-blocktime will show list of blocking
+time per vCPU.
-- 
2.49.0



  parent reply	other threads:[~2025-05-27 21:59 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-05-27 21:58 [PATCH 00/11] migration: Some enhancements and cleanups for 10.1 Peter Xu
2025-05-27 21:58 ` [PATCH 01/11] migration/hmp: Reorg "info migrate" once more Peter Xu
2025-05-28  6:07   ` Zhijian Li (Fujitsu) via
2025-05-28 15:06   ` Dr. David Alan Gilbert
2025-05-29 16:44   ` Juraj Marcin
2025-05-27 21:58 ` [PATCH 02/11] migration/hmp: Fix postcopy-blocktime per-vCPU results Peter Xu
2025-05-28  6:27   ` Markus Armbruster
2025-05-28 15:08     ` Dr. David Alan Gilbert
2025-05-28 16:51       ` Peter Xu
2025-05-27 21:58 ` Peter Xu [this message]
2025-05-29 16:45   ` [PATCH 03/11] migration/docs: Move docs for postcopy blocktime feature Juraj Marcin
2025-05-27 21:58 ` [PATCH 04/11] migration/bg-snapshot: Do not check for SKIP in iterator Peter Xu
2025-05-29 16:45   ` Juraj Marcin
2025-05-27 21:58 ` [PATCH 05/11] migration: Drop save_live_complete_postcopy hook Peter Xu
2025-05-29 14:42   ` Juraj Marcin
2025-05-29 14:48     ` Juraj Marcin
2025-05-29 15:38       ` Peter Xu
2025-05-27 21:58 ` [PATCH 06/11] migration: Rename save_live_complete_precopy to save_complete Peter Xu
2025-05-27 21:58 ` [PATCH 07/11] migration: qemu_savevm_complete*() helpers Peter Xu
2025-05-27 21:58 ` [PATCH 08/11] migration/ram: One less indent for ram_find_and_save_block() Peter Xu
2025-05-29 16:47   ` Juraj Marcin
2025-05-27 21:58 ` [PATCH 09/11] migration/ram: Add tracepoints for ram_save_complete() Peter Xu
2025-05-29 16:48   ` Juraj Marcin
2025-05-27 21:58 ` [PATCH 10/11] migration: Rewrite the migration complete detect logic Peter Xu
2025-05-29 16:48   ` Juraj Marcin
2025-05-27 21:58 ` [PATCH 11/11] migration/postcopy: Avoid clearing dirty bitmap for postcopy too Peter Xu
2025-06-02 16:23   ` Fabiano Rosas

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