On 17 August 2015 at 13:54, Slawa Olhovchenkov <s...@zxy.spb.ru> wrote: > On Mon, Aug 17, 2015 at 01:49:27PM +0200, Alban Hertroys wrote: > >> On 17 August 2015 at 13:39, Slawa Olhovchenkov <s...@zxy.spb.ru> wrote: >> >> > In any case, for 10Gb expect about 1200MGB/s. >> >> Your usage of units is confusing. Above you claim you expect 1200 > > I am use as topic starter and expect MeGaBytes per second
That's a highly unusual way of writing MB/s. There are standards for unit prefixes: k means kilo, M means Mega, G means Giga, etc. See: https://en.wikipedia.org/wiki/International_System_of_Units#Prefixes >> million gigabytes per second, or 1.2 * 10^18 Bytes/s. I don't think >> any known network interface can do that, including highly experimental >> ones. >> >> I suspect you intended to claim that you expect 1.2GB/s (Gigabytes per >> second) over that 10Gb/s (Gigabits per second) network. >> That's still on the high side of what's possible. On TCP/IP there is >> some TCP overhead, so 1.0 GB/s is probably more realistic. > > TCP give 5-7% overhead (include retrasmits). > 10^9/8*0.97 = 1.2125 In information science, Bytes are counted in multiples of 2, not 10. A kb is 1024 bits or 2^10 b. So 10 Gb is 10 * 2^30 bits. It's also not unusual to be more specific about that 2-base and use kib, Mib and Gib instead. Apparently you didn't know that... Also, if you take 5% off, you are left with (0.95 * 10 * 2^30) / 8 = 1.1875 B/s, not 0.97 * ... Your calculations were a bit optimistic. Now I have to admit I'm used to use a factor of 10 to convert from b/s to B/s (that's 20%!), but that's probably no longer correct, what with jumbo frames and all. -- If you can't see the forest for the trees, Cut the trees and you'll see there is no forest. _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
