Patch for dom0. Signed-off-by: Wei Wang <wei.wang2@amd.com> -- AMD GmbH, Germany Operating System Research Center Legal Information: Advanced Micro Devices GmbH Karl-Hammerschmidt-Str. 34 85609 Dornach b. München Geschäftsführer: Andrew Bowd, Thomas M. McCoy, Giuliano Meroni Sitz: Dornach, Gemeinde Aschheim, Landkreis München Registergericht München, HRB Nr. 43632 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jan Beulich
2010-Aug-09 11:41 UTC
Re: [Xen-devel] [PATCH 2/2] xenoprofile: Add IBS support
>>> On 30.07.10 at 15:28, Wei Wang2 <wei.wang2@amd.com> wrote: >--- a/drivers/oprofile/oprofile_files.c >+++ b/drivers/oprofile/oprofile_files.c >@@ -21,7 +21,7 @@ > #include "oprof.h" > > unsigned long fs_buffer_size = 131072; >-unsigned long fs_cpu_buffer_size = 8192; >+unsigned long fs_cpu_buffer_size = 131072;Why is this needed at all, why this much of an increase, and why not conditional upon CONFIG_XEN? Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On Monday 09 August 2010 13:41:11 Jan Beulich wrote:> >>> On 30.07.10 at 15:28, Wei Wang2 <wei.wang2@amd.com> wrote: > > > >--- a/drivers/oprofile/oprofile_files.c > >+++ b/drivers/oprofile/oprofile_files.c > >@@ -21,7 +21,7 @@ > > #include "oprof.h" > > > > unsigned long fs_buffer_size = 131072; > >-unsigned long fs_cpu_buffer_size = 8192; > >+unsigned long fs_cpu_buffer_size = 131072; > > Why is this needed at all, why this much of an increase, and why not > conditional upon CONFIG_XEN? > > JanHi Jan I had observed over 50% samples lose using following configuration: opcontrol --start --event=IBS_OP_ALL:50000 --no-vmlinux if fs_cpu_buffer_size = 8192. The same issue was also seen on native 2.6.34 kernel. In my case, extending fs_cpu_buffer_size or increasing sampling period can fix this issue. Since each IBS_OP sample will occupy 14 entries in cpu buffer compared with only 1 entry for event-based sample, I suspect that the default size of per-cpu buffer would not be enough for IBS_OP mode in minimum sampling period (50000). I simply extended fs_cpu_buffer_size just to make sure it works for current userland tools. If we intent to force a longer minimum sampling period for IBS_OP_ALL in future release of tools, we could keep fs_cpu_buffer_size = 8192. Thanks, Wei _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel