Date: Wed, 3 Feb 2021 19:08:46 GMT From: Edward Tomasz Napierala <trasz@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: ae71b794cbed - main - linux: make timerfd_settime(2) set expirations count to zero Message-ID: <202102031908.113J8kG1053714@gitrepo.freebsd.org>
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The branch main has been updated by trasz: URL: https://cgit.FreeBSD.org/src/commit/?id=ae71b794cbed19e5e25effc3438720ad452ab87c commit ae71b794cbed19e5e25effc3438720ad452ab87c Author: shu <ankohuu@outlook.com> AuthorDate: 2021-02-03 16:51:45 +0000 Commit: Edward Tomasz Napierala <trasz@FreeBSD.org> CommitDate: 2021-02-03 19:08:40 +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 --- 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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