[Lustre-devel] Large readdir RPCs project

Jeremy Filizetti jeremy.filizetti at gmail.com
Wed Sep 29 12:01:56 PDT 2010


>
>
> On the other hand, Large readdir RPCs is basic of another metadata read
> performance improvement features - "readdir+", which is quite useful for "ls
> -l" operation (for large directory), and reduce lookup/getattr RPC as much
> as possible. In such feature, MDS will pack more dir-item's attribute (not
> only name/ino as does currently by readdir, but also mode/owner, and etc)
> information back to client-side in "readdir+" RPC. That means the dir-item
> count in one "readdir+" page is less than in the traditional readdir page,
> then more pages to be sent back to client. If without "Large readdir RPCs",
> the advantage of "readdir+" will be discounted.
>

I'd be interested in working this as well but probably as a separate
effort since SOM isn't in 1.8 and that's my main focus.  In our testing, SOM
had significant benefits over the WAN and I'd expect even better from
readdir+.  I have tried Oleg's patch for asynchronous ll_glimpse_size but
oddly I've seen someone erradic performance where at times it was worse then
statahead and synchronous ll_glimpse_size.

Jeremy
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