Date: Thu, 25 Aug 2011 15:58:04 +0000 From: "b. f." <bf1783@googlemail.com> To: freebsd-arch@freebsd.org Subject: Re: Updating our TCP and socket sysctl values... Message-ID: <CAGFTUwN5oyFXQ5VrXPnFG7NwrqSLVSsK4zG2g5S7pkUrnvyPQw@mail.gmail.com> In-Reply-To: <CAGFTUwNLfmVYjP0MtHyi4RYCsUH_SJzhgte7zxeNY%2BzRYiuxUA@mail.gmail.com> References: <CAGFTUwNLfmVYjP0MtHyi4RYCsUH_SJzhgte7zxeNY%2BzRYiuxUA@mail.gmail.com>
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On 8/25/11, b. f. <bf1783@googlemail.com> wrote: >> >> I believe it's time to up these values to something that's in line with >> >> higher speed >> >> local networks, such as 10G. Perhaps it's time to move these to 2MB >> >> instead of 256K. >> >> >> >> Thoughts? >> > >> > >> > This never happened, did it? Was there a reason? >> > >> >> I went back and looked at the mail thread. I didn't see any strong >> objections >> so I think you should commit this for 9.x. >> >> np@ did point out that nmbclusters also lags on modern hardware so >> consider upping >> that at the same time. > > I thought Bruce's observation, in: > > http://lists.freebsd.org/pipermail/freebsd-arch/2011-March/011193.html > > that: > > "...there is an mostly-unrelated bufferbloat problem that is > purely local. If you have a buffer that is larger than an Ln cache (or > about half than), then actually using just a single buffer of that size > guarantees thrashing of the Ln cache, so that almost every memory access > is an Ln cache miss. Even with current hardware, a buffer of size 256K > will thrash most L1 caches and a buffer of size a few MB will thrash most > L2 caches." > > , and his suggestion for some sort of auto-tuning, deserve > consideration. Are you going to address this problem (at least the L2 > and higher cache thrashing), or give some suggestions for tuning in > UPDATING and the relevant manpages? Sorry, I should have sent this to -arch instead of -current. b.
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