On Tue, 17 Apr 2007 03:15:51 -0400 Rik van Riel <[EMAIL PROTECTED]> wrote:
> Make it possible for applications to have the kernel free memory > lazily. This reduces a repeated free/malloc cycle from freeing > pages and allocating them, to just marking them freeable. If the > application wants to reuse them before the kernel needs the memory, > not even a page fault will happen. > > This patch, together with Ulrich's glibc change, increases > MySQL sysbench performance by a factor of 2 on my quad core > test system. > > Signed-off-by: Rik van Riel <[EMAIL PROTECTED]> > > --- > Ulrich Drepper has test glibc RPMS for this functionality at: > > http://people.redhat.com/drepper/rpms > > Andrew, I have stress tested this patch for a few days now and > have not been able to find any more bugs. I believe it is ready > to be merged in -mm, and upstream at the next merge window. > > When the patch goes upstream, I will submit a small follow-up > patch to revert MADV_DONTNEED behaviour to what it did previously > and have the new behaviour trigger only on MADV_FREE: at that > point people will have to get new test RPMs of glibc. > > I've also merged Nick's "mm: madvise avoid exclusive mmap_sem". - Nick's patch also will help this problem. It could be that your patch no longer offers a 2x speedup when combined with Nick's patch. It could well be that the combination of the two is even better, but it would be nice to firm that up a bit. Chewing a page flag is an expensive thing to do. I do go on about that. But we're adding page flags at about one per year, and when we run out we're screwed - we'll need to grow the pageframe. - I need to update your patch for Nick's patch. Please confirm that down_read(mmap_sem) is sufficient for MADV_FREE. Stylistic nit: > + if (PageLazyFree(page) && !migration) { > + /* There is new data in the page. Reinstate it. */ > + if (unlikely(pte_dirty(pteval))) { > + set_pte_at(mm, address, pte, pteval); > + ret = SWAP_FAIL; > + goto out_unmap; > + } The comment should be inside the second `if' statement. As it is, It looks like we reinstate the page if (PageLazyFree(page) && !migration). - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
