From: Stefan Hajnoczi <stefanha@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Kevin Wolf" <kwolf@redhat.com>,
"Peter Maydell" <peter.maydell@linaro.org>,
"Thomas Huth" <thuth@redhat.com>, "Sergio Lopez" <slp@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
"Laurent Vivier" <lvivier@redhat.com>,
"Max Reitz" <mreitz@redhat.com>,
"Alexander Bulekov" <alxndr@bu.edu>,
"Bandan Das" <bsd@redhat.com>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Marc-André Lureau" <marcandre.lureau@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Fam Zheng" <fam@euphon.net>,
"Richard Henderson" <rth@twiddle.net>
Subject: [PULL 08/31] aio-posix: make AioHandler deletion O(1)
Date: Sat, 22 Feb 2020 08:50:07 +0000 [thread overview]
Message-ID: <20200222085030.1760640-9-stefanha@redhat.com> (raw)
In-Reply-To: <20200222085030.1760640-1-stefanha@redhat.com>
It is not necessary to scan all AioHandlers for deletion. Keep a list
of deleted handlers instead of scanning the full list of all handlers.
The AioHandler->deleted field can be dropped. Let's check if the
handler has been inserted into the deleted list instead. Add a new
QLIST_IS_INSERTED() API for this check.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Message-id: 20200214171712.541358-5-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
include/block/aio.h | 6 ++++-
include/qemu/queue.h | 3 +++
util/aio-posix.c | 53 +++++++++++++++++++++++++++++---------------
3 files changed, 43 insertions(+), 19 deletions(-)
diff --git a/include/block/aio.h b/include/block/aio.h
index 1a2ce9ca26..9dd61cee7e 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -42,6 +42,7 @@ void qemu_aio_unref(void *p);
void qemu_aio_ref(void *p);
typedef struct AioHandler AioHandler;
+typedef QLIST_HEAD(, AioHandler) AioHandlerList;
typedef void QEMUBHFunc(void *opaque);
typedef bool AioPollFn(void *opaque);
typedef void IOHandler(void *opaque);
@@ -71,7 +72,10 @@ struct AioContext {
QemuRecMutex lock;
/* The list of registered AIO handlers. Protected by ctx->list_lock. */
- QLIST_HEAD(, AioHandler) aio_handlers;
+ AioHandlerList aio_handlers;
+
+ /* The list of AIO handlers to be deleted. Protected by ctx->list_lock. */
+ AioHandlerList deleted_aio_handlers;
/* Used to avoid unnecessary event_notifier_set calls in aio_notify;
* accessed with atomic primitives. If this field is 0, everything
diff --git a/include/qemu/queue.h b/include/qemu/queue.h
index 60e794a4e3..294db54eb1 100644
--- a/include/qemu/queue.h
+++ b/include/qemu/queue.h
@@ -158,6 +158,9 @@ struct { \
} \
} while (/*CONSTCOND*/0)
+/* Is elm in a list? */
+#define QLIST_IS_INSERTED(elm, field) ((elm)->field.le_prev != NULL)
+
#define QLIST_FOREACH(var, head, field) \
for ((var) = ((head)->lh_first); \
(var); \
diff --git a/util/aio-posix.c b/util/aio-posix.c
index 58765e581e..b5cfdbd2f6 100644
--- a/util/aio-posix.c
+++ b/util/aio-posix.c
@@ -32,10 +32,10 @@ struct AioHandler
AioPollFn *io_poll;
IOHandler *io_poll_begin;
IOHandler *io_poll_end;
- int deleted;
void *opaque;
bool is_external;
QLIST_ENTRY(AioHandler) node;
+ QLIST_ENTRY(AioHandler) node_deleted;
};
#ifdef CONFIG_EPOLL_CREATE1
@@ -68,7 +68,7 @@ static bool aio_epoll_try_enable(AioContext *ctx)
QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
int r;
- if (node->deleted || !node->pfd.events) {
+ if (QLIST_IS_INSERTED(node, node_deleted) || !node->pfd.events) {
continue;
}
event.events = epoll_events_from_pfd(node->pfd.events);
@@ -196,9 +196,11 @@ static AioHandler *find_aio_handler(AioContext *ctx, int fd)
AioHandler *node;
QLIST_FOREACH(node, &ctx->aio_handlers, node) {
- if (node->pfd.fd == fd)
- if (!node->deleted)
+ if (node->pfd.fd == fd) {
+ if (!QLIST_IS_INSERTED(node, node_deleted)) {
return node;
+ }
+ }
}
return NULL;
@@ -217,7 +219,7 @@ static bool aio_remove_fd_handler(AioContext *ctx, AioHandler *node)
/* If a read is in progress, just mark the node as deleted */
if (qemu_lockcnt_count(&ctx->list_lock)) {
- node->deleted = 1;
+ QLIST_INSERT_HEAD_RCU(&ctx->deleted_aio_handlers, node, node_deleted);
node->pfd.revents = 0;
return false;
}
@@ -359,7 +361,7 @@ static void poll_set_started(AioContext *ctx, bool started)
QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
IOHandler *fn;
- if (node->deleted) {
+ if (QLIST_IS_INSERTED(node, node_deleted)) {
continue;
}
@@ -416,6 +418,26 @@ bool aio_pending(AioContext *ctx)
return result;
}
+static void aio_free_deleted_handlers(AioContext *ctx)
+{
+ AioHandler *node;
+
+ if (QLIST_EMPTY_RCU(&ctx->deleted_aio_handlers)) {
+ return;
+ }
+ if (!qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
+ return; /* we are nested, let the parent do the freeing */
+ }
+
+ while ((node = QLIST_FIRST_RCU(&ctx->deleted_aio_handlers))) {
+ QLIST_REMOVE(node, node);
+ QLIST_REMOVE(node, node_deleted);
+ g_free(node);
+ }
+
+ qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
+}
+
static bool aio_dispatch_handlers(AioContext *ctx)
{
AioHandler *node, *tmp;
@@ -427,7 +449,7 @@ static bool aio_dispatch_handlers(AioContext *ctx)
revents = node->pfd.revents & node->pfd.events;
node->pfd.revents = 0;
- if (!node->deleted &&
+ if (!QLIST_IS_INSERTED(node, node_deleted) &&
(revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&
aio_node_check(ctx, node->is_external) &&
node->io_read) {
@@ -438,21 +460,13 @@ static bool aio_dispatch_handlers(AioContext *ctx)
progress = true;
}
}
- if (!node->deleted &&
+ if (!QLIST_IS_INSERTED(node, node_deleted) &&
(revents & (G_IO_OUT | G_IO_ERR)) &&
aio_node_check(ctx, node->is_external) &&
node->io_write) {
node->io_write(node->opaque);
progress = true;
}
-
- if (node->deleted) {
- if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
- QLIST_REMOVE(node, node);
- g_free(node);
- qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
- }
- }
}
return progress;
@@ -463,6 +477,7 @@ void aio_dispatch(AioContext *ctx)
qemu_lockcnt_inc(&ctx->list_lock);
aio_bh_poll(ctx);
aio_dispatch_handlers(ctx);
+ aio_free_deleted_handlers(ctx);
qemu_lockcnt_dec(&ctx->list_lock);
timerlistgroup_run_timers(&ctx->tlg);
@@ -530,7 +545,7 @@ static bool run_poll_handlers_once(AioContext *ctx, int64_t *timeout)
RCU_READ_LOCK_GUARD();
QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
- if (!node->deleted && node->io_poll &&
+ if (!QLIST_IS_INSERTED(node, node_deleted) && node->io_poll &&
aio_node_check(ctx, node->is_external) &&
node->io_poll(node->opaque)) {
/*
@@ -664,7 +679,7 @@ bool aio_poll(AioContext *ctx, bool blocking)
if (!aio_epoll_enabled(ctx)) {
QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
- if (!node->deleted && node->pfd.events
+ if (!QLIST_IS_INSERTED(node, node_deleted) && node->pfd.events
&& aio_node_check(ctx, node->is_external)) {
add_pollfd(node);
}
@@ -741,6 +756,8 @@ bool aio_poll(AioContext *ctx, bool blocking)
progress |= aio_dispatch_handlers(ctx);
}
+ aio_free_deleted_handlers(ctx);
+
qemu_lockcnt_dec(&ctx->list_lock);
progress |= timerlistgroup_run_timers(&ctx->tlg);
--
2.24.1
next prev parent reply other threads:[~2020-02-22 8:54 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-22 8:49 [PULL 00/31] Block patches Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 01/31] virtio: increase virtqueue size for virtio-scsi and virtio-blk Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 02/31] aio-posix: avoid reacquiring rcu_read_lock() when polling Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 03/31] rcu_queue: add QSLIST functions Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 04/31] util/async: make bh_aio_poll() O(1) Stefan Hajnoczi
2020-03-16 16:42 ` Marc-André Lureau
2020-02-22 8:50 ` [PULL 05/31] aio-posix: fix use after leaving scope in aio_poll() Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 06/31] aio-posix: don't pass ns timeout to epoll_wait() Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 07/31] qemu/queue.h: add QLIST_SAFE_REMOVE() Stefan Hajnoczi
2020-02-22 8:50 ` Stefan Hajnoczi [this message]
2020-02-22 8:50 ` [PULL 09/31] aio-posix: make AioHandler dispatch O(1) with epoll Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 10/31] softmmu: move vl.c to softmmu/ Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 11/31] softmmu: split off vl.c:main() into main.c Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 12/31] module: check module wasn't already initialized Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 13/31] fuzz: add FUZZ_TARGET module type Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 14/31] qtest: add qtest_server_send abstraction Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 15/31] libqtest: add a layer of abstraction to send/recv Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 16/31] libqtest: make bufwrite rely on the TransportOps Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 17/31] qtest: add in-process incoming command handler Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 18/31] libqos: rename i2c_send and i2c_recv Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 19/31] libqos: split qos-test and libqos makefile vars Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 20/31] libqos: move useful qos-test funcs to qos_external Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 21/31] fuzz: add fuzzer skeleton Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 22/31] exec: keep ram block across fork when using qtest Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 23/31] main: keep rcu_atfork callback enabled for qtest Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 24/31] fuzz: support for fork-based fuzzing Stefan Hajnoczi
2020-02-22 11:34 ` Eric Blake
2020-02-24 11:35 ` Stefan Hajnoczi
2020-02-27 2:50 ` Alexander Bulekov
2020-02-22 8:50 ` [PULL 25/31] fuzz: add support for qos-assisted fuzz targets Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 26/31] fuzz: add target/fuzz makefile rules Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 27/31] fuzz: add configure flag --enable-fuzzing Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 28/31] fuzz: add i440fx fuzz targets Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 29/31] fuzz: add virtio-net fuzz target Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 30/31] fuzz: add virtio-scsi " Stefan Hajnoczi
2020-02-22 8:50 ` [PULL 31/31] fuzz: add documentation to docs/devel/ Stefan Hajnoczi
2020-02-22 9:13 ` [PULL 00/31] Block patches no-reply
2020-02-24 11:33 ` Stefan Hajnoczi
2020-02-24 12:47 ` Peter Maydell
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