On Tue, 2013-06-11 at 11:12 -0500, Steve Bergman wrote: > Are you saying that with XFS there is no periodic > flushing mechanism at all? And that unless there's an > fsync/fdatasync/sync or the memory needs to be reclaimed, that it can > sit in the page cache forever? I read the later responses to this and they seemed to say that the data in the page cache should be written to the disk periodically. I am not meaning to hijack the thread. I just have a question directly related to this point. I have an application that is streaming data to an XFS disk at a sustained 25 MB/sec. This is well below what the hardware supports. The application does fopen/fwrite/fclose (no active flushing or syncing). I see that as my application writes data (the only process writing the only open file on the disk), the system cache grows and grows. Here is the unusual part: periodically, writes take some number of seconds to complete, rather than the typical <50 msecs). The increased time seems to correspond to the increasing size of the page cache. If I do: echo 1 > /proc/sys/vm/drop_caches while the application is runnung, then the writes do not occasionally take longer. Until the cache grows again, and I do the echo again. I am sure I must be misinterpreting what I see. (on openSUSE 12.1. kernel 3.1.0) -- Roger Oberholtzer _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
