bf251437e9
Many changes were necessary this time around:
* QAPI was changed to avoid redundant has_* variables, see commit
44ea9d9be3 ("qapi: Start to elide redundant has_FOO in generated C")
for details. This affected many QMP commands added by Proxmox too.
* Pending querying for migration got split into two functions, one to
estimate, one for exact value, see commit c8df4a7aef ("migration:
Split save_live_pending() into state_pending_*") for details. Relevant
for savevm-async and PBS dirty bitmap.
* Some block (driver) functions got converted to coroutines, so the
Proxmox block drivers needed to be adapted.
* Alloc track auto-detaching during PBS live restore got broken by
AioContext-related changes resulting in a deadlock. The current, hacky
method was replaced by a simpler one. Stefan apparently ran into a
problem with that when he wrote the driver, but there were
improvements in the stream job code since then and I didn't manage to
reproduce the issue. It's a separate patch "alloc-track: fix deadlock
during drop" for now, you can find the details there.
* Async snapshot-related changes:
- The pending querying got adapted to the above-mentioned split and
a patch is added to optimize it/make it more similar to what
upstream code does.
- Added initialization of the compression counters (for
future-proofing).
- It's necessary the hold the BQL (big QEMU lock = iothread mutex)
during the setup phase, because block layer functions are used there
and not doing so leads to racy, hard-to-debug crashes or hangs. It's
necessary to change some upstream code too for this, a version of
the patch "migration: for snapshots, hold the BQL during setup
callbacks" is intended to be upstreamed.
- Need to take the bdrv graph read lock before flushing.
* hmp_info_balloon was moved to a different file.
* Needed to include a new headers from time to time to still get the
correct functions.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
54 lines
1.6 KiB
Diff
54 lines
1.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Stefan Reiter <s.reiter@proxmox.com>
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Date: Wed, 9 Dec 2020 11:46:57 +0100
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Subject: [PATCH] PVE: block/pbs: fast-path reads without allocation if
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possible
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...and switch over to g_malloc/g_free while at it to align with other
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QEMU code.
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Tracing shows the fast-path is taken almost all the time, though not
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100% so the slow one is still necessary.
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Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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block/pbs.c | 17 ++++++++++++++---
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1 file changed, 14 insertions(+), 3 deletions(-)
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diff --git a/block/pbs.c b/block/pbs.c
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index 43e69ada46..5d20789084 100644
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--- a/block/pbs.c
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+++ b/block/pbs.c
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@@ -201,7 +201,16 @@ static coroutine_fn int pbs_co_preadv(BlockDriverState *bs,
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BDRVPBSState *s = bs->opaque;
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int ret;
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char *pbs_error = NULL;
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- uint8_t *buf = malloc(bytes);
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+ uint8_t *buf;
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+ bool inline_buf = true;
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+
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+ /* for single-buffer IO vectors we can fast-path the write directly to it */
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+ if (qiov->niov == 1 && qiov->iov->iov_len >= bytes) {
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+ buf = qiov->iov->iov_base;
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+ } else {
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+ inline_buf = false;
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+ buf = g_malloc(bytes);
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+ }
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if (offset < 0 || bytes < 0) {
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fprintf(stderr, "unexpected negative 'offset' or 'bytes' value!\n");
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@@ -224,8 +233,10 @@ static coroutine_fn int pbs_co_preadv(BlockDriverState *bs,
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return -EIO;
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}
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- qemu_iovec_from_buf(qiov, 0, buf, bytes);
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- free(buf);
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+ if (!inline_buf) {
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+ qemu_iovec_from_buf(qiov, 0, buf, bytes);
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+ g_free(buf);
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+ }
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return 0;
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}
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