Hi Jan, On Mon, Jan 02, 2017 at 04:48:41PM +0100, Jan Kara wrote: > Hi, > > On Tue 27-12-16 16:45:03, Minchan Kim wrote: > > > Patch 3 splits the swap cache radix tree into 64MB chunks, reducing > > > the rate that we have to contende for the radix tree. > > > > To me, it's rather hacky. I think it might be common problem for page cache > > so can we think another generalized way like range_lock? Ccing Jan. > > I agree on the hackyness of the patch and that page cache would suffer with > the same contention (although the files are usually smaller than swap so it > would not be that visible I guess). But I don't see how range lock would > help here - we need to serialize modifications of the tree structure itself > and that is difficult to achieve with the range lock. So what you would > need is either a different data structure for tracking swap cache entries > or a finer grained locking of the radix tree. Thanks for the comment, Jan. I think there are more general options. One is to shrink batching pages like Mel and Tim had approached. https://patchwork.kernel.org/patch/9008421/ https://patchwork.kernel.org/patch/9322793/ Or concurrent page cache by peter. https://www.kernel.org/doc/ols/2007/ols2007v2-pages-311-318.pdf Ccing Nick who might have an interest on lockless page cache. Thanks. -- 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>