Date: Tue, 14 Mar 2006 21:28:00 -0500 From: Kris Kennaway <kris@obsecurity.org> To: JoaoBR <joao@matik.com.br> Cc: freebsd-amd64@freebsd.org Subject: Re: amd64 slower than i386 on identical AMD 64 system? Message-ID: <20060315022800.GA47353@xor.obsecurity.org> In-Reply-To: <200603141914.54442.joao@matik.com.br> References: <200603140740.38388.joao@matik.com.br> <200603141710.12822.kono@kth.se> <20060314112625.09a3ac2c.wmoran@collaborativefusion.com> <200603141914.54442.joao@matik.com.br>
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--oyUTqETQ0mS9luUI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Mar 14, 2006 at 07:14:54PM -0300, JoaoBR wrote: > I can confirm this too > SMP amd64s are having constant crashes when running >2GB and <4GB of RAM. > In order not getting anything wrong I am talking about X2-SMP mono-chip-M= Bs > this is not happening on dual-chip-MB with two separate processors. > I run the same hardware as UP-amd64 and it never crashes > Since this crashes are more frequent with IPI_PREEMPTION I have now some= =20 > servers under test running without PREEMPTION at all and appearently the= =20 > crashes are gone Right, IPI_PREEMPTION is not stable (nor is it enabled by default). Why did you decide to use it? > Overall the amd64-SMP kernels running on X2 processors are extermly sensi= tive=20 > to non polling NICs and are crashing often. The overall performance also = is=20 > bad.=20 > Soon I change this cards into polling ones, seems XL is best, I do not ha= ve=20 > crashes anymore.=20 > Funny that single 64bit AMDs are running fine with non polling NICs even = when=20 > running a SMP enabled kernel. Soon I put back the X2 ... boom. Crashing with or without the use of broken kernel options? > > We've been using ubench and pgbench (since these will be PostgreSQL > > servers) to test. We're seeing that the 64b stuff runs just a bit > > slower. We're also seeing that the amd64 doesn't seem to scale up > > to using more than one processor, but that's an issue under investigati= on > > (see other thread on this list) >=20 > this I can not confirm, I get SMP X2-amds with ULE and 4BSD running on bo= th=20 > cpus, same for dual-chip-MBs > But I can not say anything about PGSQL at all > My servers are cache servers in first place and I have some web and mail= =20 > server running amd64 and the cpu scheduling seems to work well. Overall I= =20 > have the impression that the ULE scheduler is giving better performance o= n a=20 > machine with more than 2MB/s going through You need to be very careful when claiming bad performance: ULE is well-known to perform badly on many workloads. In summary, you need to rule out whether your issues are resulting from a poor choice of non-standard kernel options, or are actually bugs in FreeBSD. Kris --oyUTqETQ0mS9luUI Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (FreeBSD) iD8DBQFEF3uwWry0BWjoQKURAo7SAJ93qYBCzo0vdKLIVgbXL2Ol3W+EAgCfRO3C Vl8qyEFpSUl/Ke+qpX5Q1nI= =WHpO -----END PGP SIGNATURE----- --oyUTqETQ0mS9luUI--
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