Mark Seger wrote: > I'm running a little script that does 3 consecutive small reads of 4K > each and then sleeps for a second and as you can see from the following > collectl output readahead is happening. How do I know? Because the > network traffic is so high: > > # <----------Network----------><-------------Lustre > Client--------------> > #Time netKBi pkt-in netKBo pkt-out Reads KBRead Writes KBWrite > Hits Misses > 09:31:54 1084 740 29 394 3 12 0 0 > 0 3 > 09:31:55 1084 740 29 394 3 12 0 0 > 0 3 > 09:31:56 1084 740 29 394 3 12 0 0 > 0 3 > 09:31:57 1084 741 29 394 2 8 0 0 > 0 2 > > I'm getting my data from > /proc/fs/lustre/llite/spfs1-00000100768c2800/read_ahead_stats and when I > look at the disards, they're not changing. What I would like to know is > why. as I'd think all that extra data would be discarded from the > cache. Is it because some other process needs to put pressure on it? These read-ahead pages will be discarded when it met memory pressure or the client revokes the lock of these pages. > I > have 4GB memory and just wrote a 5GB file which should certain force out > anything already there but the counter never changed. > If you did not change the parameters in /proc, lustre client only permit 32M dirty cache currently, you can check max_dirty_mb in /proc . So writing 5GB file will not trigger memory pressure on client. > I do see "readpage not consecutive" changing, > > -mark > > > _______________________________________________ > Lustre-discuss mailing list > [email protected] > http://lists.lustre.org/mailman/listinfo/lustre-discuss >
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