42abc95f05
wqe->lock is abused, it now protects acct->work_list, hash stuff, nr_workers, wqe->free_list and so on. Lets first get the work_list out of the wqe-lock mess by introduce a specific lock for work list. This is the first step to solve the huge contension between work insertion and work consumption. good thing: - split locking for bound and unbound work list - reduce contension between work_list visit and (worker's)free_list. For the hash stuff, since there won't be a work with same file in both bound and unbound work list, thus they won't visit same hash entry. it works well to use the new lock to protect hash stuff. Results: set max_unbound_worker = 4, test with echo-server: nice -n -15 ./io_uring_echo_server -p 8081 -f -n 1000 -l 16 (-n connection, -l workload) before this patch: Samples: 2M of event 'cycles:ppp', Event count (approx.): 1239982111074 Overhead Command Shared Object Symbol 28.59% iou-wrk-10021 [kernel.vmlinux] [k] native_queued_spin_lock_slowpath 8.89% io_uring_echo_s [kernel.vmlinux] [k] native_queued_spin_lock_slowpath 6.20% iou-wrk-10021 [kernel.vmlinux] [k] _raw_spin_lock 2.45% io_uring_echo_s [kernel.vmlinux] [k] io_prep_async_work 2.36% iou-wrk-10021 [kernel.vmlinux] [k] _raw_spin_lock_irqsave 2.29% iou-wrk-10021 [kernel.vmlinux] [k] io_worker_handle_work 1.29% io_uring_echo_s [kernel.vmlinux] [k] io_wqe_enqueue 1.06% iou-wrk-10021 [kernel.vmlinux] [k] io_wqe_worker 1.06% io_uring_echo_s [kernel.vmlinux] [k] _raw_spin_lock 1.03% iou-wrk-10021 [kernel.vmlinux] [k] __schedule 0.99% iou-wrk-10021 [kernel.vmlinux] [k] tcp_sendmsg_locked with this patch: Samples: 1M of event 'cycles:ppp', Event count (approx.): 708446691943 Overhead Command Shared Object Symbol 16.86% iou-wrk-10893 [kernel.vmlinux] [k] native_queued_spin_lock_slowpat 9.10% iou-wrk-10893 [kernel.vmlinux] [k] _raw_spin_lock 4.53% io_uring_echo_s [kernel.vmlinux] [k] native_queued_spin_lock_slowpat 2.87% iou-wrk-10893 [kernel.vmlinux] [k] io_worker_handle_work 2.57% iou-wrk-10893 [kernel.vmlinux] [k] _raw_spin_lock_irqsave 2.56% io_uring_echo_s [kernel.vmlinux] [k] io_prep_async_work 1.82% io_uring_echo_s [kernel.vmlinux] [k] _raw_spin_lock 1.33% iou-wrk-10893 [kernel.vmlinux] [k] io_wqe_worker 1.26% io_uring_echo_s [kernel.vmlinux] [k] try_to_wake_up spin_lock failure from 25.59% + 8.89% = 34.48% to 16.86% + 4.53% = 21.39% TPS is similar, while cpu usage is from almost 400% to 350% Signed-off-by: Hao Xu <haoxu@linux.alibaba.com> Link: https://lore.kernel.org/r/20220206095241.121485-2-haoxu@linux.alibaba.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.