On 02/02/2015 08:55 AM, Mel Gorman wrote: > This patch identifies when a thread is frequently calling MADV_DONTNEED > on the same region of memory and starts ignoring the hint. On an 8-core > single-socket machine this was the impact on ebizzy using glibc 2.19. The manpage, at least, claims that we zero-fill after MADV_DONTNEED is called: > MADV_DONTNEED > Do not expect access in the near future. (For the time being, the application is finished with the given range, so the kernel can free resources > associated with it.) Subsequent accesses of pages in this range will succeed, but will result either in reloading of the memory contents from the > underlying mapped file (see mmap(2)) or zero-fill-on-demand pages for mappings without an underlying file. So if we have anything depending on the behavior that it's _always_ zero-filled after an MADV_DONTNEED, this will break it. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>