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Every task_work will try to wake the task to be executed, which causes excessive scheduling and additional overhead. For some tw it's justified, but others won't do much but post a single CQE. When a task waits for multiple cqes, every such task_work will wake it up. Instead, the task may give a hint about how many cqes it waits for, io_req_local_work_add() will compare against it and skip wake ups if #cqes + #tw is not enough to satisfy the waiting condition. Task_work that uses the optimisation should be simple enough and never post more than one CQE. It's also ignored for non DEFER_TASKRUN rings. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/d2b77e99d1e86624d8a69f7037d764b739dcd225.1680782017.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/net.h>
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#include <linux/uio.h>
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#include <net/sock.h>
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#include <linux/nospec.h>
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#include "rsrc.h"
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#define IO_NOTIF_SPLICE_BATCH 32
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struct io_notif_data {
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struct file *file;
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struct ubuf_info uarg;
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unsigned long account_pages;
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bool zc_report;
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bool zc_used;
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bool zc_copied;
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};
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struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx);
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void io_notif_set_extended(struct io_kiocb *notif);
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static inline struct io_notif_data *io_notif_to_data(struct io_kiocb *notif)
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{
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return io_kiocb_to_cmd(notif, struct io_notif_data);
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}
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static inline void io_notif_flush(struct io_kiocb *notif)
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__must_hold(¬if->ctx->uring_lock)
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{
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struct io_notif_data *nd = io_notif_to_data(notif);
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/* drop slot's master ref */
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if (refcount_dec_and_test(&nd->uarg.refcnt))
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__io_req_task_work_add(notif, IOU_F_TWQ_LAZY_WAKE);
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}
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static inline int io_notif_account_mem(struct io_kiocb *notif, unsigned len)
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{
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struct io_ring_ctx *ctx = notif->ctx;
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struct io_notif_data *nd = io_notif_to_data(notif);
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unsigned nr_pages = (len >> PAGE_SHIFT) + 2;
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int ret;
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if (ctx->user) {
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ret = __io_account_mem(ctx->user, nr_pages);
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if (ret)
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return ret;
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nd->account_pages += nr_pages;
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}
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return 0;
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}
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