134 lines
4.6 KiB
Diff
134 lines
4.6 KiB
Diff
From 05efd4675b1241f2cc68fd54c92a8a834699f212 Mon Sep 17 00:00:00 2001
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From: "plai@redhat.com" <plai@redhat.com>
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Date: Thu, 29 Jul 2021 07:42:21 -0400
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Subject: [PATCH 14/39] ratelimit: protect with a mutex
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RH-Author: Miroslav Rezanina <mrezanin@redhat.com>
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RH-MergeRequest: 32: Synchronize with RHEL-AV 8.5 release 27 to RHEL 9
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RH-Commit: [6/15] 48586bf5d422cb676a6f2d2cd0abb0822cfc17b2 (mrezanin/centos-src-qemu-kvm)
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RH-Bugzilla: 1957194
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RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
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RH-Acked-by: Andrew Jones <drjones@redhat.com>
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Right now, rate limiting is protected by the AioContext mutex, which is
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taken for example both by the block jobs and by qmp_block_job_set_speed
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(via find_block_job).
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We would like to remove the dependency of block layer code on the
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AioContext mutex, since most drivers and the core I/O code are already
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not relying on it. However, there is no existing lock that can easily
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be taken by both ratelimit_set_speed and ratelimit_calculate_delay,
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especially because the latter might run in coroutine context (and
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therefore under a CoMutex) but the former will not.
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Since concurrent calls to ratelimit_calculate_delay are not possible,
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one idea could be to use a seqlock to get a snapshot of slice_ns and
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slice_quota. But for now keep it simple, and just add a mutex to the
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RateLimit struct; block jobs are generally not performance critical to
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the point of optimizing the clock cycles spent in synchronization.
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This also requires the introduction of init/destroy functions, so
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add them to the two users of ratelimit.h.
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 4951967d84a0acbf47895add9158e2d4c6056ea0)
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Signed-off-by: Paul Lai <plai@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block/block-copy.c | 2 ++
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blockjob.c | 3 +++
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include/qemu/ratelimit.h | 14 ++++++++++++++
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3 files changed, 19 insertions(+)
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diff --git a/block/block-copy.c b/block/block-copy.c
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index 39ae481c8b..9b4af00614 100644
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--- a/block/block-copy.c
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+++ b/block/block-copy.c
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@@ -230,6 +230,7 @@ void block_copy_state_free(BlockCopyState *s)
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return;
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}
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+ ratelimit_destroy(&s->rate_limit);
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bdrv_release_dirty_bitmap(s->copy_bitmap);
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shres_destroy(s->mem);
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g_free(s);
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@@ -289,6 +290,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
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s->copy_size = MAX(s->cluster_size, BLOCK_COPY_MAX_BUFFER);
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}
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+ ratelimit_init(&s->rate_limit);
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QLIST_INIT(&s->tasks);
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QLIST_INIT(&s->calls);
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diff --git a/blockjob.c b/blockjob.c
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index 207e8c7fd9..46f15befe8 100644
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--- a/blockjob.c
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+++ b/blockjob.c
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@@ -87,6 +87,7 @@ void block_job_free(Job *job)
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block_job_remove_all_bdrv(bjob);
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blk_unref(bjob->blk);
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+ ratelimit_destroy(&bjob->limit);
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error_free(bjob->blocker);
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}
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@@ -435,6 +436,8 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
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assert(job->job.driver->free == &block_job_free);
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assert(job->job.driver->user_resume == &block_job_user_resume);
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+ ratelimit_init(&job->limit);
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+
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job->blk = blk;
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job->finalize_cancelled_notifier.notify = block_job_event_cancelled;
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diff --git a/include/qemu/ratelimit.h b/include/qemu/ratelimit.h
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index 01da8d63f1..003ea6d5a3 100644
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--- a/include/qemu/ratelimit.h
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+++ b/include/qemu/ratelimit.h
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@@ -14,9 +14,11 @@
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#ifndef QEMU_RATELIMIT_H
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#define QEMU_RATELIMIT_H
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+#include "qemu/lockable.h"
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#include "qemu/timer.h"
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typedef struct {
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+ QemuMutex lock;
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int64_t slice_start_time;
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int64_t slice_end_time;
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uint64_t slice_quota;
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@@ -40,6 +42,7 @@ static inline int64_t ratelimit_calculate_delay(RateLimit *limit, uint64_t n)
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int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
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double delay_slices;
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+ QEMU_LOCK_GUARD(&limit->lock);
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assert(limit->slice_quota && limit->slice_ns);
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if (limit->slice_end_time < now) {
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@@ -65,9 +68,20 @@ static inline int64_t ratelimit_calculate_delay(RateLimit *limit, uint64_t n)
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return limit->slice_end_time - now;
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}
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+static inline void ratelimit_init(RateLimit *limit)
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+{
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+ qemu_mutex_init(&limit->lock);
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+}
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+
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+static inline void ratelimit_destroy(RateLimit *limit)
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+{
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+ qemu_mutex_destroy(&limit->lock);
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+}
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+
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static inline void ratelimit_set_speed(RateLimit *limit, uint64_t speed,
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uint64_t slice_ns)
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{
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+ QEMU_LOCK_GUARD(&limit->lock);
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limit->slice_ns = slice_ns;
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limit->slice_quota = MAX(((double)speed * slice_ns) / 1000000000ULL, 1);
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}
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--
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2.27.0
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