Han-Wen Nienhuys-5 wrote: > > On Mon, Aug 6, 2012 at 6:53 PM, Joseph Rushton Wakeling > <joseph.wakel...@webdrake.net> wrote: >> On 06/08/12 20:26, Han-Wen Nienhuys wrote: >>> >>> Also, going MT will give you a max 8x speedup (assuming perfect >>> parallelization on an 8 core machine). That is not going to bring down >>> processing costs to interactive rates. >> >> >> I think you're focusing on the wrong kind of architecture. > > I'm talking about the architecture of computers that people can buy in > the shops today. While cute, a 192-way ARM server is useless in > realistic scenarios. See eg. > http://static.googleusercontent.com/external_content/untrusted_dlcp/research.google.com/pt-BR/us/pubs/archive/36448.pdf > - aka. "Let's use 9 pregnant women, we'd have a baby within the > month." > > Unless you have a embarrassingly parallel problem to begin with (which > music typesetting is not), lots of parallelism only buys you > synchronization overhead, both lock contention at run-time, and the > overhead of having to write race-condition-free parallel code. > > Note that lilypond is embarassingly parallel at the file level, so for > the regression test, we already distribute the files on as many CPUs > as we have available. > >> _This_ is the kind of setup that you should be aiming to exploit the >> multithreaded possibilities of: >> http://www.zdnet.com/boston-virdis-192-core-server-consumes-only-300-watts-of-datacenter-power-7000001654/ > > -- > Han-Wen Nienhuys - han...@xs4all.nl - http://www.xs4all.nl/~hanwen > > _______________________________________________ > lilypond-user mailing list > lilypond-user@gnu.org > https://lists.gnu.org/mailman/listinfo/lilypond-user > >
The reason this is important is because while IPC goes up incrementally and relatively slowly (IPC has done little more than double between 2005 [P4 660] and now [i7 3930X]) and clock speed is relatively stagnant (it's unlikely we'll ever get 8GHz stock x86 CPUs the way Intel predicted), core count is the only real way to dramatically improve performance - over a similar period, core count has gone up six-fold (in high-end parts), and it's set to continue. I agree, talking about a typesetting program running on a 192-core ARM server is a bit silly, but then, so is saying that an 8-fold increase in speed won't make the process instantaneous, then implying that for this reason we shouldn't look for ways to make it work. -- View this message in context: http://old.nabble.com/Sibelius-Software-UK-office-shuts-down-tp34245636p34264057.html Sent from the Gnu - Lilypond - User mailing list archive at Nabble.com. _______________________________________________ lilypond-user mailing list lilypond-user@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-user