Zheng Liu <gnehzuil.liu@xxxxxxxxx> writes: > Hi list, > > Recently we encounter a problem about page reclaim. I abstract it in here. > The problem is that there are two different file types. One is small index > file, and another is large data file. The index file is mmaped into memory, > and application hope that they can be kept in memory and don't be reclaimed > too frequently. The data file is manipulted by read/write, and they should > be reclaimed more frequently than the index file. > > As previously discussion [1], Konstantin suggest me to mmap index file with > PROT_EXEC flag. Meanwhile he provides a patch to set a flag in mm_flags to > increase the priority of mmaped file pages. However, these solutions are > not perfect. I review the related patches (8cab4754 and c909e993) and I > think that mmaped index file with PROT_EXEC flag is too tricky. From the > view of applicaton programmer, index file is a regular file that stores > some data. So they should be mmap with PROT_READ | PROT_WRITE rather than > with PROT_EXEC. As commit log said (8cab4754), the purpose of this patch > is to keep executable code in memory to improve the response of application. > In addition, Kongstantin's patch needs to adjust the application program. > So in some cases, we cannot touch the code of application, and this patch is > useless. > > I have discussed with Kongstantin about this problem and we think maybe > kernel should provide some mechanism. For example, user can set memory > pressure priorities for vma or inode, or mmaped pages and file pages can be > reclaimed separately. If someone has thought about it, please let me know. > Any feedbacks are welcomed. Thank you. > > Previously discussion: > 1. http://marc.info/?l=linux-mm&m=132947026019538&w=2 > > Regards, > Zheng It's not exactly the same approach, but we have toyed with the idea of charging different inodes to different cgroups. Each cgroup would have different soft/hard limits to allow for different cache behavior. http://www.spinics.net/lists/linux-mm/msg06006.html -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>