Messages in this thread | | | From | David Sharp <> | Date | Mon, 6 Dec 2010 12:38:26 -0800 | Subject | Re: [PATCH 07/15] ftrace: fix event alignment: kvm:kvm_hv_hypercall |
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On Sat, Dec 4, 2010 at 12:11 AM, Avi Kivity <avi@redhat.com> wrote: > On 12/04/2010 02:13 AM, David Sharp wrote: >> >> Signed-off-by: David Sharp<dhsharp@google.com> >> --- >> arch/x86/kvm/trace.h | 8 ++++---- >> 1 files changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h >> index a6544b8..ab41fb0 100644 >> --- a/arch/x86/kvm/trace.h >> +++ b/arch/x86/kvm/trace.h >> @@ -62,21 +62,21 @@ TRACE_EVENT(kvm_hv_hypercall, >> TP_ARGS(code, fast, rep_cnt, rep_idx, ingpa, outgpa), >> >> TP_STRUCT__entry( >> - __field( __u16, code ) >> - __field( bool, fast ) >> __field( __u16, rep_cnt ) >> __field( __u16, rep_idx ) >> __field( __u64, ingpa ) >> __field( __u64, outgpa ) >> + __field( __u16, code ) >> + __field( bool, fast ) >> ), >> > > Looks like a pessimisation. > > Before: 24 bytes > After: 32 bytes > > (on a 64-bit machine, assuming no packing)
This patch is predicated on packing the event structures. And since the ring buffer is 32-bit addressable, I don't attempt to improve alignment beyond 32-bit boundaries.
> > -- > I have a truly marvellous patch that fixes the bug which this > signature is too narrow to contain. > >
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