From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Bader Subject: Re: Xen PVM: Strange lockups when running PostgreSQL load Date: Thu, 18 Oct 2012 09:38:09 +0200 Message-ID: <507FB1E1.8080700@canonical.com> References: <1350479456-4007-1-git-send-email-stefan.bader@canonical.com> <507EB27D.8050308@citrix.com> <1350482118.2460.74.camel@zakaz.uk.xensource.com> <507ECD06.2050407@canonical.com> <507ED038.8000806@citrix.com> <507FC51102000078000A235E@nat28.tlf.novell.com> <507FC71502000078000A236C@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7481951078212515671==" Return-path: In-Reply-To: <507FC71502000078000A236C@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: andrew.cooper3@citrix.com, "xen-devel@lists.xen.org" , Ian Campbell , Konrad Rzeszutek Wilk List-Id: xen-devel@lists.xenproject.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --===============7481951078212515671== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="------------enig3DF9695B8064AD7EAA24E73A" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig3DF9695B8064AD7EAA24E73A Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 18.10.2012 09:08, Jan Beulich wrote: >>>> On 18.10.12 at 09:00, "Jan Beulich" wrote: >>>>> On 17.10.12 at 17:35, Andrew Cooper wro= te: >>> In each case, the event channels are masked (no surprise given the >>> conversation so far on this thread), and have no pending events.=20 >>> Therefore, I believe we are looking at the same bug. >> >> That seems very unlikely (albeit not impossible) to me, given that >> the non-pvops kernel uses ticket locks while the pvops one doesn't. >=20 > And in fact we had a similar problem with our original ticket lock > implementation, exposed by an open coded lock in the scheduler's > run queue management. But that was really ticket lock specific, > in that the fact that a CPU could passively become the owner of > a lock while polling - that's impossible with pvops' byte locks afaict.= One of the trains of thought I had was whether it could happen that a cpu= is in polling and the task gets moved. But I don't think it can happen as the hypercall unlikely is a place where any schedule happens (preempt is none= ). And it would be much more common... One detail which I hope someone can fill in is the whole "interrupted spi= nlock" thing. Saving the last lock pointer stored on the per-cpu lock_spinners a= nd so on. Is that really only for spinlocks taken without interrupts disabled o= r do I miss something there? --------------enig3DF9695B8064AD7EAA24E73A Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://www.enigmail.net/ iQIcBAEBCgAGBQJQf7HhAAoJEOhnXe7L7s6j3rwP/0GcDz5m/WYhsWXr3JHG+cen gCRGK2xfhaQI7ePzpRlZTU74wbaZNjvZXqpNe6ZA/+hy3unre8EfdeHFNJQkvkaK kMCfQjdJga44rGc4JbAnLlv1enp7IgDxzGb/G/LjDP5Ao5sDyMRegJnftvQVBKn/ GYJRSebLXUM1ZaAvvGmHZRlgmKuGF0SJ37UhsAIT/4TeiqLRssyCTNPv71UkRFhp 0brip9LboFXUzpf7Wy6oqLIpdLBovnUmEC1hd81qVwZPgAALkwzde/wNLI+brMHO URymCdKmZ9KsMvgxn+NXGKBu1k/P6gmYDKTksXY5YlloQFILO7KLSwyBIWiEC5HO +Nxjppm5MEp2AUEGhQQrQVFdi2OwW+h1itjQRnU10BobtOpwgwCxlPJXzo+2BPQM +eYNgf4+2jc6zvpnZn9cf2pAQL6pgGwhzcePVXuVErHbyX9BJDJJzsmWeR8yFq9q BIiMQoueL3f+8jZ1qF5G0ZLtxqE7U4O7B7o2jhFmYBqru/7cfiEPAHsjnK37QCbp ZyljRFi8mSZp7wLSvz1MGdr2Fpfuz8vxSQpTFy7XfPMGLdfIVKToURL6DRPZeFW1 VHd58C2KDv1pcVkyZrgptYfhExv34e1qDmwdMxRZw0+pLSpYR1r8Qz5XxmoQCY9Q je+zk3eBcPD+EI4N87Su =u/Ih -----END PGP SIGNATURE----- --------------enig3DF9695B8064AD7EAA24E73A-- --===============7481951078212515671== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel --===============7481951078212515671==--