Hi Ilpo, On 12/11/2023 4:18 AM, Ilpo Järvinen wrote: > CAT test spawns two processes into two different control groups with > exclusive schemata. Both the processes alloc a buffer from memory > matching their allocated LLC block size and flush the entire buffer out > of caches. Since the processes are reading through the buffer only once > during the measurement and initially all the buffer was flushed, the > test isn't testing CAT. > > Rewrite the CAT test to allocate a buffer sized to half of LLC. Then > perform a sequence of tests with different LLC alloc sizes starting > from half of the CBM bits down to 1-bit CBM. Flush the buffer before > each test and read the buffer twice. Observe the LLC misses on the > second read through the buffer. As the allocated LLC block gets smaller > and smaller, the LLC misses will become larger and larger giving a > strong signal on CAT working properly. > > The new CAT test is using only a single process because it relies on > measured effect against another run of itself rather than another > process adding noise. The rest of the system is set to use the CBM bits > not used by the CAT test to keep the test isolated. > > Replace count_bits() with count_contiguous_bits() to get the first bit > position in order to be able to calculate masks based on it. > > This change has been tested with a number of systems from different > generations. > > Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx> > --- Thank you! Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> Reinette
