On Thu, Sep 08, 2016 at 11:15:52AM +0530, Anshuman Khandual wrote: > On 09/07/2016 10:16 PM, Huang, Ying wrote: > > From: Huang Ying <ying.huang@xxxxxxxxx> > > > > In this patch, the size of the swap cluster is changed to that of the > > THP (Transparent Huge Page) on x86_64 architecture (512). This is for > > the THP swap support on x86_64. Where one swap cluster will be used to > > hold the contents of each THP swapped out. And some information of the > > swapped out THP (such as compound map count) will be recorded in the > > swap_cluster_info data structure. > > > > For other architectures which want THP swap support, THP_SWAP_CLUSTER > > need to be selected in the Kconfig file for the architecture. > > > > In effect, this will enlarge swap cluster size by 2 times on x86_64. > > Which may make it harder to find a free cluster when the swap space > > becomes fragmented. So that, this may reduce the continuous swap space > > allocation and sequential write in theory. The performance test in 0day > > shows no regressions caused by this. > > This patch needs to be split into two separate ones > > (1) Add THP_SWAP_CLUSTER config option > (2) Enable CONFIG_THP_SWAP_CLUSTER for X86_64 No, don't do that. This is a bit of an anti-pattern in this series, where it introduces a thing in one patch, and a user for it in a later patch. However, in order to judge whether that thing is good or not, I need to know how exactly it's being used. So, please, split your series into logical steps, not geographical ones. When you introduce a function, config option, symbol, add it along with the code that actually *uses* it, in the same patch. It goes for this patch, but also stuff like the memcg accounting functions, get_huge_swap_page() etc. Start with the logical change, then try to isolate independent changes that could make sense even without the rest of the series. If that results in a large patch, then so be it. If a big change is hard to review, then making me switch back and forth between emails will make it harder, not easier, to make make sense of it. 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>