On Mon Jan 12, 2026 at 3:47 PM CET, Andrew Cooper wrote: > On 12/01/2026 2:43 pm, Jan Beulich wrote: >> On 12.01.2026 15:08, Alejandro Vallejo wrote: >>> Debug builds stress the wrapping logic of the TLB clock by narrowing it >>> down to 10 bits. This is inconvenient to test real time workloads on >>> such builds. >>> >>> Add Kconfig option to be able to selectively use the non-stressed >>> behaviour on debug. >>> >>> Signed-off-by: Alejandro Vallejo <[email protected]> >> Hmm, yes, why not. However, ... >> >>> --- a/xen/arch/x86/flushtlb.c >>> +++ b/xen/arch/x86/flushtlb.c >>> @@ -20,11 +20,7 @@ >>> #include <asm/spec_ctrl.h> >>> >>> /* Debug builds: Wrap frequently to stress-test the wrap logic. */ >>> -#ifdef NDEBUG >>> -#define WRAP_MASK (0xFFFFFFFFU) >>> -#else >>> -#define WRAP_MASK (0x000003FFU) >>> -#endif >>> +#define WRAP_MASK (IS_ENABLED(CONFIG_DEBUG_TLB_CLK) ? 0x3FFU : UINT32_MAX) >> ... the comment then will want updating as well, I'd say. It doesn't go >> terribly stale this way, but at least slightly. I'd suggest to minimally >> drop "builds".
I left the comment because the rationale still holds. Dropping "builds" sounds good to me. > > I'm suggest just dropping WRAP_MASK. > > We've done this locally in the XenServer patchqueue since 2011 or so due > to the overhead, and I don't think it's interesting enough to warrant a > separate option. > > ~Andrew I don't mind much either way. I need it gone for my needs and I don't care much how it happens. Jan + Roger, do you have strong opinions on the matter? Cheers, Alejandro
