On Thu, 2022-07-07 at 17:23 -0600, Jens Axboe wrote:
> For recvmsg/sendmsg, if they don't complete inline, we currently need
> to allocate a struct io_async_msghdr for each request. This is a
> somewhat large struct.
>
> Hook up sendmsg/recvmsg to use the io_alloc_cache. This reduces the
> alloc + free overhead considerably, yielding 4-5% of extra
> performance
> running netbench.
>
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
> ---
> include/linux/io_uring_types.h | 6 ++-
> io_uring/io_uring.c | 3 ++
> io_uring/net.c | 73 +++++++++++++++++++++++++++++---
> --
> io_uring/net.h | 11 ++++-
> 4 files changed, 81 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/io_uring_types.h
> b/include/linux/io_uring_types.h
> index bf8f95332eda..d54b8b7e0746 100644
> --- a/include/linux/io_uring_types.h
> +++ b/include/linux/io_uring_types.h
> @@ -222,8 +222,7 @@ struct io_ring_ctx {
> struct io_hash_table cancel_table_locked;
> struct list_head cq_overflow_list;
> struct io_alloc_cache apoll_cache;
> - struct xarray personalities;
> - u32 pers_next;
> + struct io_alloc_cache netmsg_cache;
> } ____cacheline_aligned_in_smp;
>
> /* IRQ completion list, under ->completion_lock */
> @@ -241,6 +240,9 @@ struct io_ring_ctx {
> unsigned int file_alloc_start;
> unsigned int file_alloc_end;
>
> + struct xarray personalities;
> + u32 pers_next;
> +
> struct {
> /*
> * We cache a range of free CQEs we can use, once
> exhausted it
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index b5098773d924..32110c5b4059 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -89,6 +89,7 @@
> #include "kbuf.h"
> #include "rsrc.h"
> #include "cancel.h"
> +#include "net.h"
>
> #include "timeout.h"
> #include "poll.h"
> @@ -297,6 +298,7 @@ static __cold struct io_ring_ctx
> *io_ring_ctx_alloc(struct io_uring_params *p)
> INIT_LIST_HEAD(&ctx->cq_overflow_list);
> INIT_LIST_HEAD(&ctx->io_buffers_cache);
> io_alloc_cache_init(&ctx->apoll_cache);
> + io_alloc_cache_init(&ctx->netmsg_cache);
> init_completion(&ctx->ref_comp);
> xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
> mutex_init(&ctx->uring_lock);
> @@ -2473,6 +2475,7 @@ static __cold void io_ring_ctx_free(struct
> io_ring_ctx *ctx)
> __io_cqring_overflow_flush(ctx, true);
> io_eventfd_unregister(ctx);
> io_flush_apoll_cache(ctx);
> + io_flush_netmsg_cache(ctx);
> mutex_unlock(&ctx->uring_lock);
> io_destroy_buffers(ctx);
> if (ctx->sq_creds)
> diff --git a/io_uring/net.c b/io_uring/net.c
> index 6679069eeef1..ba7e94ff287c 100644
> --- a/io_uring/net.c
> +++ b/io_uring/net.c
> @@ -12,6 +12,7 @@
>
> #include "io_uring.h"
> #include "kbuf.h"
> +#include "alloc_cache.h"
> #include "net.h"
>
> #if defined(CONFIG_NET)
> @@ -97,18 +98,57 @@ static bool io_net_retry(struct socket *sock, int
> flags)
> return sock->type == SOCK_STREAM || sock->type ==
> SOCK_SEQPACKET;
> }
>
> +static void io_netmsg_recycle(struct io_kiocb *req, unsigned int
> issue_flags)
> +{
> + struct io_async_msghdr *hdr = req->async_data;
> +
> + if (!hdr || issue_flags & IO_URING_F_UNLOCKED)
> + return;
> +
> + if (io_alloc_cache_store(&req->ctx->netmsg_cache)) {
> + hlist_add_head(&hdr->cache_list, &req->ctx-
> >netmsg_cache.list);
can io_alloc_cache_store just do the store?
would be nicer to have cache::list be generally unused outside of the
cache code.
> + req->async_data = NULL;
> + req->flags &= ~REQ_F_ASYNC_DATA;
> + }
> +}
> +
> +static struct io_async_msghdr *io_recvmsg_alloc_async(struct
> io_kiocb *req,
> + unsigned int
> issue_flags)
> +{
> + struct io_ring_ctx *ctx = req->ctx;
> +
> + if (!(issue_flags & IO_URING_F_UNLOCKED) &&
> + !hlist_empty(&ctx->netmsg_cache.list)) {
> + struct io_async_msghdr *hdr;
> +
> + hdr = hlist_entry(ctx->netmsg_cache.list.first,
> + struct io_async_msghdr,
> cache_list);
> + ctx->netmsg_cache.nr_cached--;
> + hlist_del(&hdr->cache_list);
ditto here. I think all the hlist stuff and the nr_cached manipulation
can be wrapped up
> + req->flags |= REQ_F_ASYNC_DATA;
> + req->async_data = hdr;
> + return hdr;
> + }
> +
> + if (!io_alloc_async_data(req))
> + return req->async_data;
> +
> + return NULL;
> +}
> +
> static int io_setup_async_msg(struct io_kiocb *req,
> - struct io_async_msghdr *kmsg)
> + struct io_async_msghdr *kmsg,
> + unsigned int issue_flags)
> {
> struct io_async_msghdr *async_msg = req->async_data;
>
> if (async_msg)
> return -EAGAIN;
> - if (io_alloc_async_data(req)) {
> + async_msg = io_recvmsg_alloc_async(req, issue_flags);
> + if (!async_msg) {
> kfree(kmsg->free_iov);
> return -ENOMEM;
> }
> - async_msg = req->async_data;
> req->flags |= REQ_F_NEED_CLEANUP;
> memcpy(async_msg, kmsg, sizeof(*kmsg));
> async_msg->msg.msg_name = &async_msg->addr;
> @@ -195,7 +235,7 @@ int io_sendmsg(struct io_kiocb *req, unsigned int
> issue_flags)
>
> if (!(req->flags & REQ_F_POLLED) &&
> (sr->flags & IORING_RECVSEND_POLL_FIRST))
> - return io_setup_async_msg(req, kmsg);
> + return io_setup_async_msg(req, kmsg, issue_flags);
>
> flags = sr->msg_flags;
> if (issue_flags & IO_URING_F_NONBLOCK)
> @@ -207,13 +247,13 @@ int io_sendmsg(struct io_kiocb *req, unsigned
> int issue_flags)
>
> if (ret < min_ret) {
> if (ret == -EAGAIN && (issue_flags &
> IO_URING_F_NONBLOCK))
> - return io_setup_async_msg(req, kmsg);
> + return io_setup_async_msg(req, kmsg,
> issue_flags);
> if (ret == -ERESTARTSYS)
> ret = -EINTR;
> if (ret > 0 && io_net_retry(sock, flags)) {
> sr->done_io += ret;
> req->flags |= REQ_F_PARTIAL_IO;
> - return io_setup_async_msg(req, kmsg);
> + return io_setup_async_msg(req, kmsg,
> issue_flags);
> }
> req_set_fail(req);
> }
> @@ -221,6 +261,7 @@ int io_sendmsg(struct io_kiocb *req, unsigned int
> issue_flags)
> if (kmsg->free_iov)
> kfree(kmsg->free_iov);
> req->flags &= ~REQ_F_NEED_CLEANUP;
> + io_netmsg_recycle(req, issue_flags);
> if (ret >= 0)
> ret += sr->done_io;
> else if (sr->done_io)
> @@ -495,7 +536,7 @@ int io_recvmsg(struct io_kiocb *req, unsigned int
> issue_flags)
>
> if (!(req->flags & REQ_F_POLLED) &&
> (sr->flags & IORING_RECVSEND_POLL_FIRST))
> - return io_setup_async_msg(req, kmsg);
> + return io_setup_async_msg(req, kmsg, issue_flags);
>
> if (io_do_buffer_select(req)) {
> void __user *buf;
> @@ -519,13 +560,13 @@ int io_recvmsg(struct io_kiocb *req, unsigned
> int issue_flags)
> ret = __sys_recvmsg_sock(sock, &kmsg->msg, sr->umsg, kmsg-
> >uaddr, flags);
> if (ret < min_ret) {
> if (ret == -EAGAIN && force_nonblock)
> - return io_setup_async_msg(req, kmsg);
> + return io_setup_async_msg(req, kmsg,
> issue_flags);
> if (ret == -ERESTARTSYS)
> ret = -EINTR;
> if (ret > 0 && io_net_retry(sock, flags)) {
> sr->done_io += ret;
> req->flags |= REQ_F_PARTIAL_IO;
> - return io_setup_async_msg(req, kmsg);
> + return io_setup_async_msg(req, kmsg,
> issue_flags);
> }
> req_set_fail(req);
> } else if ((flags & MSG_WAITALL) && (kmsg->msg.msg_flags &
> (MSG_TRUNC | MSG_CTRUNC))) {
> @@ -535,6 +576,7 @@ int io_recvmsg(struct io_kiocb *req, unsigned int
> issue_flags)
> /* fast path, check for non-NULL to avoid function call */
> if (kmsg->free_iov)
> kfree(kmsg->free_iov);
> + io_netmsg_recycle(req, issue_flags);
> req->flags &= ~REQ_F_NEED_CLEANUP;
> if (ret > 0)
> ret += sr->done_io;
> @@ -848,4 +890,17 @@ int io_connect(struct io_kiocb *req, unsigned
> int issue_flags)
> io_req_set_res(req, ret, 0);
> return IOU_OK;
> }
> +
> +void io_flush_netmsg_cache(struct io_ring_ctx *ctx)
> +{
> + while (!hlist_empty(&ctx->netmsg_cache.list)) {
> + struct io_async_msghdr *hdr;
> +
> + hdr = hlist_entry(ctx->netmsg_cache.list.first,
> + struct io_async_msghdr,
> cache_list);
> + hlist_del(&hdr->cache_list);
> + kfree(hdr);
> + }
> + ctx->netmsg_cache.nr_cached = 0;
> +}
again - could be put somewhere common. I assume there will not be much
more cleanup than simple kfree
> #endif
> diff --git a/io_uring/net.h b/io_uring/net.h
> index 81d71d164770..576efb602c7f 100644
> --- a/io_uring/net.h
> +++ b/io_uring/net.h
> @@ -5,7 +5,10 @@
>
> #if defined(CONFIG_NET)
> struct io_async_msghdr {
> - struct iovec fast_iov[UIO_FASTIOV];
> + union {
> + struct iovec fast_iov[UIO_FASTIOV];
> + struct hlist_node cache_list;
> + };
> /* points to an allocated iov, if NULL we use fast_iov
> instead */
> struct iovec *free_iov;
> struct sockaddr __user *uaddr;
> @@ -40,4 +43,10 @@ int io_socket(struct io_kiocb *req, unsigned int
> issue_flags);
> int io_connect_prep_async(struct io_kiocb *req);
> int io_connect_prep(struct io_kiocb *req, const struct io_uring_sqe
> *sqe);
> int io_connect(struct io_kiocb *req, unsigned int issue_flags);
> +
> +void io_flush_netmsg_cache(struct io_ring_ctx *ctx);
> +#else
> +static inline void io_flush_netmsg_cache(struct io_ring_ctx *ctx)
> +{
> +}
> #endif
