https://bugzilla.novell.com/show_bug.cgi?id=713546 https://bugzilla.novell.com/show_bug.cgi?id=713546#c0 Summary: On SLES 11 SP1 on x86-64: PAT Incorrect configuration of PAT msr on last cpu core during boot Classification: openSUSE Product: openSUSE 11.3 Version: Final Platform: x86-64 OS/Version: SLES 11 Status: NEW Severity: Major Priority: P5 - None Component: Other AssignedTo: bnc-team-screening@forge.provo.novell.com ReportedBy: ram.vepa@qlogic.com QAContact: qa@suse.de Found By: --- Blocker: --- User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110621 Fedora/3.6.18-1.fc14 Firefox/3.6.18 We applied this patch, https://lkml.org/lkml/2011/4/13/232, and found that it fixes this problem. Please apply it to your next update. This patch was accepted upstream to the 2.6.38.3 kernel. We found this problem on all dual socket systems we have tested in our lab. To name a few systems - quad core Intel Xeon X5570 @ 2.93GHz 2 socket, 6 core Intel Nehalem @ 1.596 GHz 2 socket. The systems boot up with all the CPU core's page attribute field, PA1 set to Write Combined while the last CPU core always comes up with the PA1 configured to Write Through. This inconsistency in the PAT configuration across the CPUs causes bad performance for PIO writes impacting latency, message rates and small message bandwidth when the last CPU is used. Reproducible: Always Steps to Reproduce: 1. Power up system. 2. Read the contents of MSR 0x277 on all cores. Actual Results: The output should look like this - [ 201.806700] ib_qib: PAT on cpu id: 0 70106:70106 [ 201.806706] ib_qib: PAT on cpu id: 2 70106:70106 [ 201.806709] ib_qib: PAT on cpu id: 1 70106:70106 [ 201.806713] ib_qib: PAT on cpu id: 3 70106:70106 [ 201.806716] ib_qib: PAT on cpu id: 5 70106:70106 [ 201.806719] ib_qib: PAT on cpu id: 4 70106:70106 [ 201.806723] ib_qib: PAT on cpu id: 6 70106:70106 [ 201.806726] ib_qib: PAT on cpu id: 7 70406:70406 ==> Inconsistency! Expected Results: [ 201.806700] ib_qib: PAT on cpu id: 0 70106:70106 [ 201.806706] ib_qib: PAT on cpu id: 2 70106:70106 [ 201.806709] ib_qib: PAT on cpu id: 1 70106:70106 [ 201.806713] ib_qib: PAT on cpu id: 3 70106:70106 [ 201.806716] ib_qib: PAT on cpu id: 5 70106:70106 [ 201.806719] ib_qib: PAT on cpu id: 4 70106:70106 [ 201.806723] ib_qib: PAT on cpu id: 6 70106:70106 [ 201.806726] ib_qib: PAT on cpu id: 7 70106:70106 ==> This is correct -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.