On 09/30/2013 03:02 AM, Mel Gorman wrote: > I am afraid I never looked too closely once I learned that the primary > motivation for this was relieving iTLB pressure in a very specific > case. AFAIK, this is not a problem in the vast majority of modern CPUs > and I found it very hard to be motivated to review the series as a result. > I suspected that in many cases that the cost of IO would continue to dominate > performance instead of TLB pressure. I also found it unlikely that there > was a workload that was tmpfs based that used enough memory to be hurt > by TLB pressure. My feedback was that a much more compelling case for the > series was needed but this discussion all happened on IRC unfortunately. FWIW, I'm mostly intrigued by the possibilities of how this can speed up _software_, and I'm rather uninterested in what it can do for the TLB. Page cache is particularly painful today, precisely because hugetlbfs and anonymous-thp aren't available there. If you have an app with hundreds of GB of files that it wants to mmap(), even if it's in the page cache, it takes _minutes_ to just fault in. One example: https://lkml.org/lkml/2013/6/27/698 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
