Date: Fri, 19 Mar 2021 18:42:39 GMT From: Dmitry Chagin <dchagin@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 0cb6fa6acc93 - stable/13 - linux: make timerfd_settime(2) set expirations count to zero Message-ID: <202103191842.12JIgdwG059634@gitrepo.freebsd.org>
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The branch stable/13 has been updated by dchagin: URL: https://cgit.FreeBSD.org/src/commit/?id=0cb6fa6acc93231242ef40e77518a9016ef4076a commit 0cb6fa6acc93231242ef40e77518a9016ef4076a Author: shu <ankohuu@outlook.com> AuthorDate: 2021-02-03 16:51:45 +0000 Commit: Dmitry Chagin <dchagin@FreeBSD.org> CommitDate: 2021-03-19 18:36:11 +0000 linux: make timerfd_settime(2) set expirations count to zero On Linux, read(2) from a timerfd file descriptor returns an unsigned 8-byte integer (uint64_t) containing the number of expirations that have occurred, if the timer has already expired one or more times since its settings were last modified using timerfd_settime(), or since the last successful read(2). That's to say, once we do a read or call timerfd_settime(), timer fd's expiration count should be zero. Some Linux applications create timerfd and add it to epoll with LT mode, when event comes, they do timerfd_settime instead of read to stop event source from trigger. On FreeBSD, timerfd_settime(2) didn't set the count to zero, which caused high CPU utilization. Submitted by: ankohuu_outlook.com (Shunchao Hu) Differential Revision: https://reviews.freebsd.org/D28231 (cherry picked from commit ae71b794cbed19e5e25effc3438720ad452ab87c) --- sys/compat/linux/linux_event.c | 1 + 1 file changed, 1 insertion(+) diff --git a/sys/compat/linux/linux_event.c b/sys/compat/linux/linux_event.c index dfb4588392cc..54f6b083adf3 100644 --- a/sys/compat/linux/linux_event.c +++ b/sys/compat/linux/linux_event.c @@ -981,6 +981,7 @@ linux_timerfd_settime(struct thread *td, struct linux_timerfd_settime_args *args linux_timerfd_curval(tfd, &ots); tfd->tfd_time = nts; + tfd->tfd_count = 0; if (timespecisset(&nts.it_value)) { linux_timerfd_clocktime(tfd, &cts); ts = nts.it_value;
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