Re: why we use two ObjectStore::Transaction in ReplicatedBackend::submit_transaction?

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On Sun, 1 Nov 2015, ??? wrote:
> Yes, I think so.
> keeping them separate and pass them to
> ObjectStore::queue_transactions() would increase the time on
> transaction encode process and exhaust more cpu.
> 
> The transaction::append holds 0.8% cpu on my environment.
> The transaction encoding is also really a bottleneck which process
> holds 1.8% cpu on my environment.

Where is the append() caller you're looking at?  I'm not seeing it.

sage


> 
> 2015-11-01 4:42 GMT+08:00 Sage Weil <sage@xxxxxxxxxxxx>:
> > On Sat, 31 Oct 2015, Ning Yao wrote:
> >> Yeah, since issue_op is called before log_operation, we may consider
> >> to reuse op_t after sent encoded op_t to the wire. local_t.append(),
> >> at least, does copy the op_bl in op_t transaction and we may avoid
> >> this memory copy, and if we can avoid this append operation as well as
> >> in sub_op_modify_impl(), it, at least, improves the performance 1%~2%
> >> under my testing environment using ssd as Filestore backend.
> >> The only difference we find in this path is that local_t should be
> >> done first, but actually it seems that the order of the transaction is
> >> not quite important. If so, we may refactor and improve this?
> >
> > I seem to recall that in teh EC case the order does matter (I had switched
> > the append order when trying to fix this before but had to revert because
> > things broke).
> >
> > And I'm a bit nervous about re-using local_t and relying on the send vs
> > submit timing.  Is it not practical to keep them separate and
> > pass them both down to ObjectStore::queue_transactions()?
> >
> > sage
> 
> 
> 
> -- 
> Regards,
> xinze
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