On Mon, Feb 10, 2014 at 12:28:55PM -0500, Don Zickus wrote: > With the introduction of NUMA systems, came the possibility of remote memory > accesses. > Combine those remote memory accesses with contention on the remote node (ie a > modified > cacheline) and you have a possibility for very long latencies. These > latencies can > bottleneck a program. > > The program added by these patches, helps detect the situation where two > nodes are > 'tugging' on the same _data_ cacheline. The term used through out this > program and > the various changelogs is called a HITM. This means nodeX went to read a > cacheline > and it was discovered to be loaded in nodeY's LLC cache (hence the cacheHIT). > The > remote cacheline was also in a 'M'odified state thus creating a 'HIT M' for > hit in > a modified state. HITMs can happen locally and remotely. This program's > interest > is mainly in remote HITMs as they cause the longest latencies.
All of that is true of the traditional SMP system too. Just use lower level caches. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
