Date: Tue, 23 Jun 2009 21:33:26 +0000 (UTC) From: Ed Schouten <ed@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r194769 - head/sys/kern Message-ID: <200906232133.n5NLXQXf090765@svn.freebsd.org>
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Author: ed Date: Tue Jun 23 21:33:26 2009 New Revision: 194769 URL: http://svn.freebsd.org/changeset/base/194769 Log: Use dcdwait to block threads to serialize writes. I suspect the usage of bgwait causes a lot of spurious wakeups when threads are blocked in the background, because they will be woken up each time a write() call is performed. Also wakeup dcdwait when the TTY is abandoned. Modified: head/sys/kern/tty.c Modified: head/sys/kern/tty.c ============================================================================== --- head/sys/kern/tty.c Tue Jun 23 21:24:21 2009 (r194768) +++ head/sys/kern/tty.c Tue Jun 23 21:33:26 2009 (r194769) @@ -335,6 +335,7 @@ ttydev_close(struct cdev *dev, int fflag tp->t_revokecnt++; tty_wakeup(tp, FREAD|FWRITE); cv_broadcast(&tp->t_bgwait); + cv_broadcast(&tp->t_dcdwait); ttydev_leave(tp); @@ -455,7 +456,7 @@ ttydev_write(struct cdev *dev, struct ui } else { /* Serialize write() calls. */ while (tp->t_flags & TF_BUSY_OUT) { - error = tty_wait(tp, &tp->t_bgwait); + error = tty_wait(tp, &tp->t_dcdwait); if (error) goto done; } @@ -463,7 +464,7 @@ ttydev_write(struct cdev *dev, struct ui tp->t_flags |= TF_BUSY_OUT; error = ttydisc_write(tp, uio, ioflag); tp->t_flags &= ~TF_BUSY_OUT; - cv_broadcast(&tp->t_bgwait); + cv_broadcast(&tp->t_dcdwait); } done: tty_unlock(tp);
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