6.10-stable review patch. If anyone has any objections, please let me know.
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From: Pavel Begunkov asml.silence@gmail.com
[ Upstream commit 342b2e395d5f34c9f111a818556e617939f83a8c ]
It's more natural to use ktime/ns instead of keeping around usec, especially since we're comparing it against user provided timers, so convert napi busy poll internal handling to ktime. It's also nicer since the type (ktime_t vs unsigned long) now tells the unit of measure.
Keep everything as ktime, which we convert to/from micro seconds for IORING_[UN]REGISTER_NAPI. The net/ busy polling works seems to work with usec, however it's not real usec as shift by 10 is used to get it from nsecs, see busy_loop_current_time(), so it's easy to get truncated nsec back and we get back better precision.
Note, we can further improve it later by removing the truncation and maybe convincing net/ to use ktime/ns instead.
Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/95e7ec8d095069a3ed5d40a4bc6f8b586698bc7e.172200377... Signed-off-by: Jens Axboe axboe@kernel.dk Stable-dep-of: 84f2eecf9501 ("io_uring/napi: check napi_enabled in io_napi_add() before proceeding") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/io_uring_types.h | 2 +- io_uring/io_uring.h | 2 +- io_uring/napi.c | 48 +++++++++++++++++++--------------- io_uring/napi.h | 2 +- 4 files changed, 30 insertions(+), 24 deletions(-)
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index 7abdc09271245..b18e998c8b887 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -410,7 +410,7 @@ struct io_ring_ctx { spinlock_t napi_lock; /* napi_list lock */
/* napi busy poll default timeout */ - unsigned int napi_busy_poll_to; + ktime_t napi_busy_poll_dt; bool napi_prefer_busy_poll; bool napi_enabled;
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h index 726e6367af4d3..af46d03d58847 100644 --- a/io_uring/io_uring.h +++ b/io_uring/io_uring.h @@ -43,7 +43,7 @@ struct io_wait_queue { ktime_t timeout;
#ifdef CONFIG_NET_RX_BUSY_POLL - unsigned int napi_busy_poll_to; + ktime_t napi_busy_poll_dt; bool napi_prefer_busy_poll; #endif }; diff --git a/io_uring/napi.c b/io_uring/napi.c index 327e5f3a8abe0..6bdb267e9c33c 100644 --- a/io_uring/napi.c +++ b/io_uring/napi.c @@ -33,6 +33,12 @@ static struct io_napi_entry *io_napi_hash_find(struct hlist_head *hash_list, return NULL; }
+static inline ktime_t net_to_ktime(unsigned long t) +{ + /* napi approximating usecs, reverse busy_loop_current_time */ + return ns_to_ktime(t << 10); +} + void __io_napi_add(struct io_ring_ctx *ctx, struct socket *sock) { struct hlist_head *hash_list; @@ -102,14 +108,14 @@ static inline void io_napi_remove_stale(struct io_ring_ctx *ctx, bool is_stale) __io_napi_remove_stale(ctx); }
-static inline bool io_napi_busy_loop_timeout(unsigned long start_time, - unsigned long bp_usec) +static inline bool io_napi_busy_loop_timeout(ktime_t start_time, + ktime_t bp) { - if (bp_usec) { - unsigned long end_time = start_time + bp_usec; - unsigned long now = busy_loop_current_time(); + if (bp) { + ktime_t end_time = ktime_add(start_time, bp); + ktime_t now = net_to_ktime(busy_loop_current_time());
- return time_after(now, end_time); + return ktime_after(now, end_time); }
return true; @@ -124,7 +130,8 @@ static bool io_napi_busy_loop_should_end(void *data, return true; if (io_should_wake(iowq) || io_has_work(iowq->ctx)) return true; - if (io_napi_busy_loop_timeout(start_time, iowq->napi_busy_poll_to)) + if (io_napi_busy_loop_timeout(net_to_ktime(start_time), + iowq->napi_busy_poll_dt)) return true;
return false; @@ -181,10 +188,12 @@ static void io_napi_blocking_busy_loop(struct io_ring_ctx *ctx, */ void io_napi_init(struct io_ring_ctx *ctx) { + u64 sys_dt = READ_ONCE(sysctl_net_busy_poll) * NSEC_PER_USEC; + INIT_LIST_HEAD(&ctx->napi_list); spin_lock_init(&ctx->napi_lock); ctx->napi_prefer_busy_poll = false; - ctx->napi_busy_poll_to = READ_ONCE(sysctl_net_busy_poll); + ctx->napi_busy_poll_dt = ns_to_ktime(sys_dt); }
/* @@ -217,7 +226,7 @@ void io_napi_free(struct io_ring_ctx *ctx) int io_register_napi(struct io_ring_ctx *ctx, void __user *arg) { const struct io_uring_napi curr = { - .busy_poll_to = ctx->napi_busy_poll_to, + .busy_poll_to = ktime_to_us(ctx->napi_busy_poll_dt), .prefer_busy_poll = ctx->napi_prefer_busy_poll }; struct io_uring_napi napi; @@ -232,7 +241,7 @@ int io_register_napi(struct io_ring_ctx *ctx, void __user *arg) if (copy_to_user(arg, &curr, sizeof(curr))) return -EFAULT;
- WRITE_ONCE(ctx->napi_busy_poll_to, napi.busy_poll_to); + WRITE_ONCE(ctx->napi_busy_poll_dt, napi.busy_poll_to * NSEC_PER_USEC); WRITE_ONCE(ctx->napi_prefer_busy_poll, !!napi.prefer_busy_poll); WRITE_ONCE(ctx->napi_enabled, true); return 0; @@ -249,14 +258,14 @@ int io_register_napi(struct io_ring_ctx *ctx, void __user *arg) int io_unregister_napi(struct io_ring_ctx *ctx, void __user *arg) { const struct io_uring_napi curr = { - .busy_poll_to = ctx->napi_busy_poll_to, + .busy_poll_to = ktime_to_us(ctx->napi_busy_poll_dt), .prefer_busy_poll = ctx->napi_prefer_busy_poll };
if (arg && copy_to_user(arg, &curr, sizeof(curr))) return -EFAULT;
- WRITE_ONCE(ctx->napi_busy_poll_to, 0); + WRITE_ONCE(ctx->napi_busy_poll_dt, 0); WRITE_ONCE(ctx->napi_prefer_busy_poll, false); WRITE_ONCE(ctx->napi_enabled, false); return 0; @@ -275,23 +284,20 @@ int io_unregister_napi(struct io_ring_ctx *ctx, void __user *arg) void __io_napi_adjust_timeout(struct io_ring_ctx *ctx, struct io_wait_queue *iowq, struct timespec64 *ts) { - unsigned int poll_to = READ_ONCE(ctx->napi_busy_poll_to); + ktime_t poll_dt = READ_ONCE(ctx->napi_busy_poll_dt);
if (ts) { struct timespec64 poll_to_ts;
- poll_to_ts = ns_to_timespec64(1000 * (s64)poll_to); + poll_to_ts = ns_to_timespec64(ktime_to_ns(poll_dt)); if (timespec64_compare(ts, &poll_to_ts) < 0) { s64 poll_to_ns = timespec64_to_ns(ts); - if (poll_to_ns > 0) { - u64 val = poll_to_ns + 999; - do_div(val, 1000); - poll_to = val; - } + if (poll_to_ns > 0) + poll_dt = ns_to_ktime(poll_to_ns); } }
- iowq->napi_busy_poll_to = poll_to; + iowq->napi_busy_poll_dt = poll_dt; }
/* @@ -320,7 +326,7 @@ int io_napi_sqpoll_busy_poll(struct io_ring_ctx *ctx) LIST_HEAD(napi_list); bool is_stale = false;
- if (!READ_ONCE(ctx->napi_busy_poll_to)) + if (!READ_ONCE(ctx->napi_busy_poll_dt)) return 0; if (list_empty_careful(&ctx->napi_list)) return 0; diff --git a/io_uring/napi.h b/io_uring/napi.h index 6fc0393d0dbef..babbee36cd3eb 100644 --- a/io_uring/napi.h +++ b/io_uring/napi.h @@ -55,7 +55,7 @@ static inline void io_napi_add(struct io_kiocb *req) struct io_ring_ctx *ctx = req->ctx; struct socket *sock;
- if (!READ_ONCE(ctx->napi_busy_poll_to)) + if (!READ_ONCE(ctx->napi_busy_poll_dt)) return;
sock = sock_from_file(req->file);