Hello, On Tue 16-06-15 16:32:18, Peter Xu wrote: > I just want to know whether there is better way to make Linux VFS read > ahead more aggressive (from my reading the source code, the maximum > read ahead of file is statically set to 2MB). E.g., to change the read > ahead window to 64MB. No, there is no way to tune automatic readahead window to more than 2 MB. You can still ask the kernel explicitely via posix_fadvise(2) to prefetch the data for you though. > What I am doing is tuning CEPHFS read performance, however, remote is > very poor (100+MB) comparing to local test (374MB). I am testing using > dd (this should also the case for most real-life scenarios), so an > aggressive read ahead policy should be really help for me to make the > IO asynchronous and make the backend disks running concurrently. So you have some larger chunks in which file is split and you need to fetch them from different servers, do I understand it correctly? Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
