Date: Fri, 03 Mar 2017 15:40:55 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-virtualization@FreeBSD.org Subject: [Bug 216759] [kern] Memory speed with small blocks (1K) up to 35 times slower than host system (under QEMU emulation, but not only) Message-ID: <bug-216759-27103-5J6Xblk4zT@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-216759-27103@https.bugs.freebsd.org/bugzilla/> References: <bug-216759-27103@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D216759 --- Comment #13 from bob.cauthen@gmail.com <bob.cauthen@gmail.com> --- As an interested party to this bug I have to raise an issue with this poten= tial workaround. First though... thanks everybody who discovered and tested this... BUT According to timecounters(4): kern.timecounter.tc.X.quality is an integral value, defining the quali= ty of this time counter compared to others. A negative value means this time counter is broken and should not be used. Andrew's test output showed this line: Timecounter "TSC-low" frequency 1700064513 Hz quality -100 If the workaround forces the use of TSC-low, and it's kern.timecounter.tc.X.quality is negative, are we not advocating a workarou= nd with a broken timecounter as measured by the OS? If the answer is yes (to my rhetorical question) possible follow-up questio= ns might then be: - Should we trust the negative "quality" measurement? (if not, maybe it's easier to mod the timecounter measurement code??) - Has anyone done any longer term testing with the TSC-low timer in this configuration to see if using that time counter effects anything else in a running system? Sorry to be the opposing voice here (especially because this bug affects me too). --=20 You are receiving this mail because: You are the assignee for the bug.=
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