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    SubjectRe: [RFC PATCH 00/20] Intel(R) Resource Director Technology Cache Pseudo-Locking enabling
    On Mon, 12 Feb 2018, Reinette Chatre wrote:
    > On 1/16/2018 3:38 AM, Thomas Gleixner wrote:
    > All tests involve a user space application that allocates (malloc() with
    > mlockall()) or in the case of Cache Pseudo-Locking maps using mmap()) a
    > 256KB region of memory. The application then randomly accesses this
    > region, 32 bytes at a time, measuring the latency in cycles of each
    > access using the rdtsc instruction. Each time a test is run it is
    > repeated ten times.
    > In both the PALLOC and CAT tests there was improvement (CAT most
    > significant) in latency accessing a 256KB memory region but in both
    > (PALLOC and CAT) 512KB of cache was set aside for application to obtain
    > these results. Using Cache Pseudo-Locking to access the 256KB memory
    > region only 256KB of cache was set aside while also reducing the access
    > latency when compared to both PALLOC and CAT.
    >
    > I do hope these results establishes the value of Cache Pseudo-Locking to
    > you.

    Very nice. Thank you so much for doing this. That kind of data is really
    valuable.

    My take away from this: All of the mechanisms are only delivering best
    effort and the real benefit is the reduction of average latency. The worst
    case outliers are in the same ballpark at seems.

    > The rebased patch series used in this testing will be sent out
    > this week.

    I'll make sure to have cycles available for review.

    Thanks,

    tglx

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