On Tue, 29 Jan 2013 15:40:26 -0600 Seth Jennings <sjenning@xxxxxxxxxxxxxxxxxx> wrote: > This patchset adds support for flush pages out of the compressed > pool to the swap device I do so hate that word "flush". Sometimes it means "writeback", other times it means "invalidate". And perhaps it means "copy elsewhere then reclaim". Please describe with great specificity what this patch actually does with pages, and why it does it. And where the compression factors into this. The code appears to take a compressed page, decompress it into swapcache via some means. And then, for unexplained reasons, it starts writeback of that swapcache page. In zswap_flush_entry() there is a comment "page is already in the swap cache, ignore for now". This is very interesting. How and why does this come about? Does it imply that there are two copies of the same data floating around? If so, how come? Preferably all the above would be understandable by reading mm/zswap.c. -- 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>