Date: Thu, 26 Sep 2013 02:11:35 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Eduardo Morras <emorrasg@yahoo.es> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: this 48-core box... Message-ID: <CAJ-VmokS3rhLe9wQLu3uXFXVZt0qYv1T-sHSeoKtu-dMHzGyOw@mail.gmail.com> In-Reply-To: <20130922141034.d98d472e42c784062d66651c@yahoo.es> References: <52388C9B.6030205@foxbatcapital.com> <20130919155327.115e7344@sarvision.nl> <alpine.BSF.2.00.1309191157410.56073@btw.pki2.com> <20130920110535.42c984da@sarvision.nl> <CAJ-VmonDO3rbbctx-m3HF=7_m2EfjVh0n=yaM4=FhJdOtXnK8w@mail.gmail.com> <20130922141034.d98d472e42c784062d66651c@yahoo.es>
next in thread | previous in thread | raw e-mail | index | archive | help
The cache alignment happens because it hits a specific size threshold, and jemalloc/phkmalloc(I think!) just round everything up to be page size aligned. The underlying problem may actually be a code change to how the math is done. It just runs slower on page-aligned alignments.. adrian On 22 September 2013 05:10, Eduardo Morras <emorrasg@yahoo.es> wrote: > On Sat, 21 Sep 2013 12:53:36 -0700 > Adrian Chadd <adrian@freebsd.org> wrote: > > > .. just as a data point - there was a thread a while ago about numeric > > processing performance on linux vs bsd. > > > > It all boiled down to how jemalloc versus the linux allocator(s) allocate > > blocks. jemalloc will page align things after a certain size. Linux > didn't. > > So when doing numeric processing, there was a lot of cache aliasing going > > on leading to inefficient cache usage and redundant memory operations. > > > > When the same workload on Linux was run on FreeBSD but with the Linux > > library/allocators, the performance was identical. > > > > No-one followed through. I think I may have to write a blog post about > it. > > There's no MALLOC_OPTIONS flag to set/unset this, but adding a new flag to > disable a feature is easier (or should be) than implementing new one. The > only problem I see to this is if the cache align happens at sbrk/mmap level. > > > > > > -adrian > > _______________________________________________ > > freebsd-questions@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > > To unsubscribe, send any mail to " > freebsd-questions-unsubscribe@freebsd.org" > > > --- --- > Eduardo Morras <emorrasg@yahoo.es> > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to " > freebsd-questions-unsubscribe@freebsd.org" >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAJ-VmokS3rhLe9wQLu3uXFXVZt0qYv1T-sHSeoKtu-dMHzGyOw>