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 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/
