> - Quickly identify all user processes mapping a given page.
Can be done with /proc/*/pagemap today. Maybe it's not "quick"
because it won't use the rmap chains, but is that a serious
issue?
> - Determine if and where the kernel maps the page, which is also
> important given the opportunity to r
Pasha Tatashin writes:
> Page Detective is a new kernel debugging tool that provides detailed
> information about the usage and mapping of physical memory pages.
>
> It is often known that a particular page is corrupted, but it is hard to
> extract more information about such a page from live sys
On Thu, Feb 21, 2019 at 02:37:45PM +0100, Peter Zijlstra wrote:
> On Thu, Feb 21, 2019 at 08:12:25AM -0500, Prarit Bhargava wrote:
> > Users cannot disable multiple CPU features with the kernel parameter
> > clearcpuid=. For example, "clearcpuid=154 clearcpuid=227" only disables
> > CPUID bit 154.
> You can always force disable SSB. In that case, all the child processes
> will have SSBD on.
Okay that sounds reasonable, given the below. Thanks.
-Andi
>
> >
> > Do you have a real use case where this behavior is a problem?
> >
> > -Andi
>
> Yes, we have an enterprise application partner th
On Wed, Dec 19, 2018 at 02:09:50PM -0500, Waiman Long wrote:
> With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode,
> the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned.
>
> As only certain class of applications (like Java) requires disabling
> speculative
Yang Zhang writes:
> Some latency-intensive workload will see obviously performance
> drop when running inside VM. The main reason is that the overhead
> is amplified when running inside VM. The most cost i have seen is
> inside idle path.
You could test with https://lkml.org/lkml/2017/7/9/2
> The same arguments would seem to apply to TASK_ISOLATION_ALL;
> note that applications don't actually go into task isolation mode
> without issuing the appropriate prctl(), so it shouldn't be too
That's a fair point. If it's entirely opt-in it's probably ok.
-Andi
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Chris Metcalf writes:
>
> +config TASK_ISOLATION_ALL
> + bool "Provide task isolation on all CPUs by default (except CPU 0)"
> + depends on TASK_ISOLATION
> + help
> + If the user doesn't pass the task_isolation boot option to
> + define the range of task isolation CPUs, co
