Date: Wed, 1 Mar 2017 13:50:30 -0500 From: Allan Jude <allanjude@freebsd.org> To: freebsd-virtualization@freebsd.org Subject: Re: Timer problems on FreeBSD 11R on KVM Message-ID: <4cc78ba2-a23b-5cb2-92c8-6435762e2910@freebsd.org> In-Reply-To: <20170301174640.GA44226@hades.panopticon> References: <20170301174640.GA44226@hades.panopticon>
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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --xpQA30Cv1tnuGUkv5JiX3pWTXT1Jv7BJK Content-Type: multipart/mixed; boundary="JAVBoaMBxLnr6rKUAmCOfePVsDmirRUJJ"; protected-headers="v1" From: Allan Jude <allanjude@freebsd.org> To: freebsd-virtualization@freebsd.org Message-ID: <4cc78ba2-a23b-5cb2-92c8-6435762e2910@freebsd.org> Subject: Re: Timer problems on FreeBSD 11R on KVM References: <20170301174640.GA44226@hades.panopticon> In-Reply-To: <20170301174640.GA44226@hades.panopticon> --JAVBoaMBxLnr6rKUAmCOfePVsDmirRUJJ Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 2017-03-01 12:46, Dmitry Marakasov wrote: > Hi! >=20 > I'm running a bunch of FreeBSD VMs on VPS provider which uses KVM. > Recently one of them began bahaving strangely. Symptoms: >=20 > - Much ~(30%) CPU spent in intr > - top shows CPU used by "intr{swi4: clock (0)}" > - kernel: calcru: runtime went backwards from 13958 usec to 10792 usec = for pid 919 (sshd) > messages in logs > - There's no much load, no high network traffic, systat shows no excess= > interrupts. > - This intr load is sporadic in form of ~30 minute busts each several > hours > - The box had ntpd running, but disabling it doesn't help > - Playing with timer-related sysctls does not help either >=20 > I've tried i8254 and TSC-low timecounters: >=20 > kern.timecounter.hardware: ACPI-fast > kern.timecounter.choice: TSC-low(800) i8254(0) ACPI-fast(900) dummy(-10= 00000) >=20 > and kern.eventtimer.periodic=3D1 >=20 > to no effect. >=20 >=20 > I suspect that this began after some changes on the hoster's side. >=20 > - This VM was working for more than a year without problems before > - A graph which monitors a reply time of website running on that VM > showed min. response time jump from 50 to 75 msec on Monday, after > which problems began. >=20 > So while I'm getting the hoster to tell me what they have changed, any > ideas? >=20 Look at: kern.eventtimer.choice and try different kern.eventtimer.timer values --=20 Allan Jude --JAVBoaMBxLnr6rKUAmCOfePVsDmirRUJJ-- --xpQA30Cv1tnuGUkv5JiX3pWTXT1Jv7BJK Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (MingW32) iQIcBAEBAgAGBQJYtxf5AAoJEBmVNT4SmAt+9uUP/1QscRM1DRs66TMvKuxXCjG+ oN+KoVPRi+ogjhXFMPHh/HNURuXxNLCGFdvnv3flPkh1VYzYRRshrI7zmX9akgR+ y1jmfYv5bUS9pqvxwixhzxQzmD+xT0ZXmJ76vK+wUkkP14I3kAv5Dff/cLkkLmZn EgYp+fhRrkLV/DOywApiUrqPSBUV06JjbVAeKMN1sOlOCFTZ6rnS9N+ICEI3185u hRcDFVoDNw61sVcpehERYa+uDLdWDbZ3ElnlFOBnKeu5zp+qJX8S6ApmKpTrbDn/ IyaS96cULIL+EzDZI4h9+NF2Py0K6GVPsHnjwgaj/RfMC1pOnrNuxng49Z2QgL1W YZDet0v+9Catg5WCb6nqbQ//YBn4vGPIqio79NMiBGG6JKov3HesCLAr7Cas/1eF i1apHhhGLbZGJSnmYtkj8gZzRNHJINGN8A92H/ZrJj8yGexJViMmpxwBFt6hXdLO 7OLjPdX7RzppAmsy7abWzRbvEx1aYbywz1vuX0AEor4Bhlwocz4lPwgrWv5e9HmI /X2cmTOwdxp2XPPM8lPwDvKeHK6cKahpCjOR3kGeaJUkCkqxfzJjHTL0cqHf7Bgx fPjVUqZYzU9C+6+FIvhuwzchgjIu/Myg5yxJNkzWgskt8uzT2KanyrgYxcHMM+HX 6t98fa5m/8npHtsF0Nmx =EFha -----END PGP SIGNATURE----- --xpQA30Cv1tnuGUkv5JiX3pWTXT1Jv7BJK--
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