[ovs-dev] [RFC] jsonrpc: make jsonrpc input_buffer size parametric

[Ben Pfaff]

On Tue, Nov 05, 2019 at 07:42:51PM +0200, Lorenzo Bianconi wrote:
> >
> > On Tue, Nov 05, 2019 at 04:27:51PM +0200, Lorenzo Bianconi wrote:
> > > Allow jsonrpc clients (e.g. ovn-controller) to specify jsonrpc input
> > > buffer size in order to reduce overhead when downloading huge db size
> > > since current value is 512B. The user can specify rpc buffer size using
> > > ovsdb_idl_set_remote routine passing requested value
> > >
> > > Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi at redhat.com>
> >
> > Hmm, I thought that we had decided to just try a 4096-byte buffer to
> > start.  That would be a much smaller patch.  The marginal benefits of
> > buffers larger than that probably decline a lot since the processing
> > cost of 4096 bytes of JSON is probably a lot more than the overhead of a
> > system call.  I imagine that any further benefit is probably from being
> > able to process more JSON per trip through the main loop.  Those same
> > benefits could also be obtained by increasing the 'for' loop limit in
> > jsonrpc_recv() from 50 to some larger number.
> 
> Hi Ben,
> 
> thanks for the review. I tried to get a PoC (this is why I sent it as
> RFC) but since the IDL/reconnect code is pretty spread
> I ended up with a large patch. I agree we can just set the bufsize to 4096.
> If it is ok for everybody I will post a patch to set the buffer size
> to one page.

I suspect that will be fine.