Can you send multiple records in one data transfer to achieve whatever gains are desired?
On Wed, Nov 23, 2016 at 12:30 AM, Nikos Mavrogiannopoulos <n...@redhat.com> wrote: > On Wed, 2016-11-23 at 10:05 +0200, Yoav Nir wrote: > > Hi, Nikos > > > > On 23 Nov 2016, at 9:06, Nikos Mavrogiannopoulos <n...@redhat.com> > > wrote: > > > > > > > > Hi, > > > Up to the current draft of TLS1.3 the record layer is restricted > > > to > > > sending 2^14 or less. Is the 2^14 number something we want to > > > preserve? > > > 16kb used to be a lot, but today if one wants to do fast data > > > transfers > > > most likely he would prefer to use larger blocks. Given that the > > > length > > > field allows for sizes up to 2^16, shouldn't the draft allow for > > > 2^16- > > > 1024 as maximum? > > > > I am not opposed to this, but looking at real browsers and servers, > > we see that they tend to set the size of records to fit IP packets. > > IP packets can carry up to 64kb of data. I believe you may be referring > to ethernet MTU sizes. That to my understanding is a way to reduce > latency in contrast to cpu costs. An increase to packet size targets > bandwidth rather than latency (speed). > > > The gains from increasing the size of records from the ~1460 bytes > > that fit in a packet to nearly 64KB are not all that great, and the > > gains from increasing records from 16 KB to 64KB are almost > > negligible. At that size the block encryption dominates the CPU time. > > Do you have measurements to support that? I'm quite surprized by such a > general statement because packetization itself is a non-negligible cost > especially when encryption is fast (i.e., in most modern CPUs with > dedicated instructions). > > regards, > Nikos > > _______________________________________________ > TLS mailing list > TLS@ietf.org > https://www.ietf.org/mailman/listinfo/tls >
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