I found several of Bryan Ford's ideas interesting as always here, particularly Structured Streams (https://bford.info/pub/net/sst-abs/) and Breaking Up the Transport Logjam (https://bford.info/pub/net/logjam-abs/)
On Wed, Jan 27, 2021 at 4:53 PM <o...@eigenstate.org> wrote: > Quoth David Arroyo <dr...@aqwari.net>: > > On Tue, Dec 29, 2020, at 18:50, cigar562hfsp952f...@icebubble.org wrote: > > > It's well-known that 9P has trouble transferring large files (high > > > volume/high bandwith) over high-latency networks, such as the Internet. > > > > From what I know of 9P, I don't think this is the fault of the protocol > > itself. In fact, since 9P lets the clients choose Fid and Tag > identifiers, > > it should be uniquely well suited for "long fat pipes". You could avoid > > waiting for round-trips by optimistically assuming your requests succeed. > > For example, you could do the following to optimistically read the first > > 8K bytes of a file without needing to wait for a response from the > server. > > > > * Twalk tag=1 fid=0 newfid=1 /path/to/somefile > > * Topen tag=2 fid=1 o_read > > * Tread tag=3 fid=1 off=0 count=4096 > > * Tread tag=4 fid=1 off=4096 count=4096 > > * Tclunk tag=5 fid=1 > > > > I'm not aware of any client implementations that do this kind of > > pipelining, though. > > > > David > > This also has some hairy edge cases. For example, > what happens to the actions in the pipeline if one > of the operations fails? > > I think that for this kind of pipelining to be > effective, 9p may need some notion of 'bundles', > where the first failure, short write, or other > exceptional operation would cause all other > commands in the bundle to be ignored. > > Another issue is that its' difficult to retrofit > this pipelining into the plan 9 system call > interface; when do you return an error from > read(2)? what if there are mutiple Treads? > > Finally, there's the problem of flow control; > with 9p, round trip time limits starvation, > at least to a degree. But how do you handle > congestion if you can stuff as many 9p packets > down a single connection as possible? There's > no packet loss, but you can end up with very > long delays as small reads like /dev/mouse > get queued behind bulk transfers. > > There are some programs that try to handle this > for 'well behaved' file systems (eg, fcp(1), > or http://src.a-b.xyz/clone/, but making it > happen in general is not trivial. > ------------------------------------------ 9fans: 9fans Permalink: https://9fans.topicbox.com/groups/9fans/Te69bb0fce0f0ffaf-M40bb94bd40d97df72c885f69 Delivery options: https://9fans.topicbox.com/groups/9fans/subscription
