Date: Mon, 26 Aug 2019 10:44:09 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 240121] Serial console can eat a lot of cpu with law baudrate Message-ID: <bug-240121-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D240121 Bug ID: 240121 Summary: Serial console can eat a lot of cpu with law baudrate Product: Base System Version: 11.2-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: nicolas.masse@stormshield.eu Since https://svnweb.freebsd.org/base?view=3Drevision&revision=3D317659, de= vices connected through a serial device and using a low baudrate seems to eat a l= ot more cpu than before. This has been constated using a lcd screen with a baudrate of 2400. Using pmc, I got this: PMC: [CPU_CLK_UNHALTED.THREAD_P] Samples: 14 (100.0%) , 0 unresolved %SAMP CALLTREE 85.7 amd64_syscall@kernel sys_write kern_writev dofilewrite devfs_write_f ttydev_write ttydisc_write tty_wait _cv_wait_sig __mtx_lock_sleep lock_delay(85.7%)=20 7.1 _start@xxx <no relevent information here>(7.1%)=20 7.1 _start@xxx <no relevent information here>(7.1%)=20 Reverting this commit made the call to lock_delay disappear and the performances of my test system back to normal. --=20 You are receiving this mail because: You are the assignee for the bug.=
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