On Thu, Jun 18, 2020 at 04:39:35PM +, David Laight wrote:
> From: Alexey Dobriyan
> > Sent: 18 June 2020 14:17
> ...
> > > > diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
> > > > index fff28c6f73a2..b0dfac3d3df7 100644
> > > > --- a/arch/x86/lib/usercopy_64.c
> > > >
From: Alexey Dobriyan
> Sent: 18 June 2020 14:17
...
> > > diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
> > > index fff28c6f73a2..b0dfac3d3df7 100644
> > > --- a/arch/x86/lib/usercopy_64.c
> > > +++ b/arch/x86/lib/usercopy_64.c
> > > @@ -24,6 +24,7 @@ unsigned long
On Thu, Jun 18, 2020 at 10:48:05AM +, David Laight wrote:
> From: Matt Fleming
> > Sent: 18 June 2020 11:20
> > x86 CPUs can suffer severe performance drops if a tight loop, such as
> > the ones in __clear_user(), straddles a 16-byte instruction fetch
> > window, or worse, a 64-byte cacheline.
From: Matt Fleming
> Sent: 18 June 2020 11:20
> x86 CPUs can suffer severe performance drops if a tight loop, such as
> the ones in __clear_user(), straddles a 16-byte instruction fetch
> window, or worse, a 64-byte cacheline. This issues was discovered in the
> SUSE kernel with the following
x86 CPUs can suffer severe performance drops if a tight loop, such as
the ones in __clear_user(), straddles a 16-byte instruction fetch
window, or worse, a 64-byte cacheline. This issues was discovered in the
SUSE kernel with the following commit,
1153933703d9 ("x86/asm/64: Micro-optimize
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