https://jira.whamcloud.com This file is an XML representation of an issue en-us 9.4.14 940014 05-12-2023 https://jira.whamcloud.com/browse/LUDOC-142 Lustre Documentation <p>Lustre 2.x manual, section:<br/> 31.2.2. Watching the Client RPC Stream</p> <p>The parameter "offset" doesn't have any description.</p> <p>It should have a description, ideally a quick summary. It should also point to the section in the manual that deals with offsets (currently 31.2.3. Client Read-Write Offset Survey).</p> LUDOC-142

Watching the Client RPC Stream (Ch 31)

Bug Minor Resolved Fixed Linda Bebernes Brett Lee QContent Mon, 22 Apr 2013 16:04:22 +0000 Tue, 27 Aug 2013 18:30:37 +0000 Tue, 27 Aug 2013 18:30:37 +0000 0 2 <p>rpc_stats - "offset" metric refers to reads or writes not accessing the next sequential location, indicating small or random IO.</p> <p>From Andreas:<br/> this is the offset of the pages within the 1MB "ideal" range, and can either indicate small IOs from the application (whether sequential or not) and/or random IOs for ideally-formed 1MB (or larger) client IOs the offset would always be 0. </p> <p>I misinterpreted.</p> <p>From Andreas (in a follow up):<br/> It might be that "offset"<br/> &gt; is relative to the previous read/write as you propose, or it could be the offset<br/> &gt; within the 1MB RPC. I would suspect the latter, because this gives a bounded<br/> &gt; range of values, and is the only critical metric for the RPC stack. Doing 1MB<br/> &gt; sized and aligned write RPCs (i.e. "offset = 0" per my definition) but with<br/> &gt; random file offsets should give nearly the same performance vs. 1MB<br/> &gt; sequential writes. In contrast, doing smaller RPCs would cause read-modify-<br/> &gt; write cycles on the underlying RAID device and should be avoided.</p> <p>Brett is now trying to understand what "bounded range of values" means, and also whether an RPC can be comprised of a several small IO's (each presumably an offset?)...</p> <p>"Offset" needs to be defined in the table in Section 31.2.2: Watching the Client RPC Stream.</p> <p>Ready for review at <a href="http://review.whamcloud.com/#/c/7362" class="external-link" target="_blank" rel="nofollow noopener">http://review.whamcloud.com/#/c/7362</a></p> <p>Issue has been fixed and merged.</p> Business Value 4.9 Development Rank 1|hzvomv: Rank (Obsolete) 7816 Severity