qemu-kvm/kvm-linux-aio-add-IO_CMD_FDSYNC-command-support.patch
Miroslav Rezanina f91321559e * Tue Jun 25 2024 Miroslav Rezanina <mrezanin@redhat.com> - 9.0.0-5
- kvm-linux-aio-add-IO_CMD_FDSYNC-command-support.patch [RHEL-42411]
- kvm-Revert-monitor-use-aio_co_reschedule_self.patch [RHEL-34618 RHEL-38697]
- kvm-aio-warn-about-iohandler_ctx-special-casing.patch [RHEL-34618 RHEL-38697]
- kvm-block-crypto-create-ciphers-on-demand.patch [RHEL-36159]
- kvm-crypto-block-drop-qcrypto_block_open-n_threads-argum.patch [RHEL-36159]
- Resolves: RHEL-42411
  (qemu-kvm: linux-aio: add support for IO_CMD_FDSYNC command)
- Resolves: RHEL-34618
  (aio=io_uring: Assertion failure `luringcb->co->ctx == s->aio_context' with block_resize)
- Resolves: RHEL-38697
  (aio=native: Assertion failure `laiocb->co->ctx == laiocb->ctx->aio_context' with block_resize)
- Resolves: RHEL-36159
  (qemu crash on Assertion `block->n_free_ciphers > 0' failed in guest installation with luks and iothread-vq-mapping)
2024-06-25 04:30:30 -04:00

128 lines
4.6 KiB
Diff

From 287ebf9f0b8a62dc49fd7802472c1ae57f653e44 Mon Sep 17 00:00:00 2001
From: Prasad Pandit <pjp@fedoraproject.org>
Date: Thu, 25 Apr 2024 12:34:12 +0530
Subject: [PATCH 1/5] linux-aio: add IO_CMD_FDSYNC command support
RH-Author: Prasad Pandit <None>
RH-MergeRequest: 249: linux-aio: add IO_CMD_FDSYNC command support
RH-Jira: RHEL-42411
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Commit: [1/1] 9beff6506d2eca7741b1c11b5acdc19b635c7c75 (pjp/cs-qemu-kvm)
Libaio defines IO_CMD_FDSYNC command to sync all outstanding
asynchronous I/O operations, by flushing out file data to the
disk storage. Enable linux-aio to submit such aio request.
When using aio=native without fdsync() support, QEMU creates
pthreads, and destroying these pthreads results in TLB flushes.
In a real-time guest environment, TLB flushes cause a latency
spike. This patch helps to avoid such spikes.
Jira: https://issues.redhat.com/browse/RHEL-42411
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Prasad Pandit <pjp@fedoraproject.org>
Message-ID: <20240425070412.37248-1-ppandit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 24687abf237e3c15816d689a8e4b08d7c3190dcb)
Signed-off-by: Prasad Pandit <pjp@fedoraproject.org>
---
block/file-posix.c | 9 +++++++++
block/linux-aio.c | 21 ++++++++++++++++++++-
include/block/raw-aio.h | 1 +
3 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index 35684f7e21..9831b08fb6 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -159,6 +159,7 @@ typedef struct BDRVRawState {
bool has_discard:1;
bool has_write_zeroes:1;
bool use_linux_aio:1;
+ bool has_laio_fdsync:1;
bool use_linux_io_uring:1;
int page_cache_inconsistent; /* errno from fdatasync failure */
bool has_fallocate;
@@ -718,6 +719,9 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
ret = -EINVAL;
goto fail;
}
+ if (s->use_linux_aio) {
+ s->has_laio_fdsync = laio_has_fdsync(s->fd);
+ }
#else
if (s->use_linux_aio) {
error_setg(errp, "aio=native was specified, but is not supported "
@@ -2599,6 +2603,11 @@ static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs)
if (raw_check_linux_io_uring(s)) {
return luring_co_submit(bs, s->fd, 0, NULL, QEMU_AIO_FLUSH);
}
+#endif
+#ifdef CONFIG_LINUX_AIO
+ if (s->has_laio_fdsync && raw_check_linux_aio(s)) {
+ return laio_co_submit(s->fd, 0, NULL, QEMU_AIO_FLUSH, 0);
+ }
#endif
return raw_thread_pool_submit(handle_aiocb_flush, &acb);
}
diff --git a/block/linux-aio.c b/block/linux-aio.c
index ec05d946f3..e3b5ec9aba 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -384,6 +384,9 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
case QEMU_AIO_READ:
io_prep_preadv(iocbs, fd, qiov->iov, qiov->niov, offset);
break;
+ case QEMU_AIO_FLUSH:
+ io_prep_fdsync(iocbs, fd);
+ break;
/* Currently Linux kernel does not support other operations */
default:
fprintf(stderr, "%s: invalid AIO request type 0x%x.\n",
@@ -412,7 +415,7 @@ int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
AioContext *ctx = qemu_get_current_aio_context();
struct qemu_laiocb laiocb = {
.co = qemu_coroutine_self(),
- .nbytes = qiov->size,
+ .nbytes = qiov ? qiov->size : 0,
.ctx = aio_get_linux_aio(ctx),
.ret = -EINPROGRESS,
.is_read = (type == QEMU_AIO_READ),
@@ -486,3 +489,19 @@ void laio_cleanup(LinuxAioState *s)
}
g_free(s);
}
+
+bool laio_has_fdsync(int fd)
+{
+ struct iocb cb;
+ struct iocb *cbs[] = {&cb, NULL};
+
+ io_context_t ctx = 0;
+ io_setup(1, &ctx);
+
+ /* check if host kernel supports IO_CMD_FDSYNC */
+ io_prep_fdsync(&cb, fd);
+ int ret = io_submit(ctx, 1, cbs);
+
+ io_destroy(ctx);
+ return (ret == -EINVAL) ? false : true;
+}
diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h
index 20e000b8ef..626706827f 100644
--- a/include/block/raw-aio.h
+++ b/include/block/raw-aio.h
@@ -60,6 +60,7 @@ void laio_cleanup(LinuxAioState *s);
int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
int type, uint64_t dev_max_batch);
+bool laio_has_fdsync(int);
void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context);
void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context);
#endif
--
2.39.3