Zheng Liu wrote:
Hi all, Currently, we encounter a problem about page reclaim. In our product system, there is a lot of applictions that manipulate a number of files. In these files, they can be divided into two categories. One is index file, another is block file. The number of index files is about 15,000, and the number of block files is about 23,000 in a 2TB disk. The application accesses index file using mmap(2), and read/write block file using pread(2)/pwrite(2). We hope to hold index file in memory as much as possible, and it works well in Redhat 2.6.18-164. It is about 60-70% of index files that can be hold in memory. However, it doesn't work well in Redhat 2.6.32-133. I know in 2.6.18 that the linux uses an active list and an inactive list to handle page reclaim, and in 2.6.32 that they are divided into anonymous list and file list. So I am curious about why most of index files can be hold in 2.6.18? The index file should be replaced because mmap doesn't impact the lru list.
There was my patch for fixing similar problem with shared/executable mapped pages "vmscan: promote shared file mapped pages" commit 34dbc67a644f and commit c909e99364c maybe it will help in your case.
BTW, I have some problems that need to be discussed. 1. I want to let index and block files are separately reclaimed. Is there any ways to satisify me in current upstream? 2. Maybe we can provide a mechansim to let different files to be mapped into differnet nodes. we can provide a ioctl(2) to tell kernel that this file should be mapped into a specific node id. A nid member is added into addpress_space struct. When alloc_page is called, the page can be allocated from that specific node id. 3. Currently the page can be reclaimed according to pid in memcg. But it is too coarse. I don't know whether memcg could provide a fine granularity page reclaim mechansim. For example, the page is reclaimed according to inode number. I don't subscribe this mailing list, So please Cc me. Thank you. Regards, Zheng -- 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>
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