Excellent, thanks! Scott
On Jan 7, 2011, at 10:28 AM, Phil Carns wrote: > Sorry about the vagueness there :) > > Maybe the better way to put it is that each BMI _method_ (bmi_tcp, > bmi_mx, etc.) is expected to provide reliable, ordered delivery with > flow control. Neither the upper layer of BMI nor the users of BMI > provide those things, other than the fact that upper levels of PVFS will > at least timeout, cancel, and retry operations if they don't complete in > a reasonable amount of time. That's a pretty crude last resort for that > kind of scenario, though. > > Most of the current BMI methods rely on their respective underlying > protocols for flow control, but if you were writing a method for > something like UDP that has no flow control at all, then you would have > to implement it yourself in the method. > > The flow component (despite its name) doesn't really do flow control. > It maybe gets part of the way there simply by capping the number of > buffers (and therefore number of messages) in flight for each I/O > request as part of its pipelining mechanism, but it doesn't keep up with > tokens or anything that tell it about the state of the remote peer. > It's just trying to make reasonable use of local resources. > > -Phil > > On 01/07/2011 09:06 AM, Atchley, Scott wrote: >> Phil, >> >> bmi-design.tex has this paragraph: >> >> "BMI provides reliability, message ordering, and flow control. If a >> particular underlying protocol does not provide one of these features, then >> BMI is responsible for implementing it." >> >> Does BMI actually provide flow control? Does it rely on the method to >> provide flow control? If so, I don't think I did anything with bmi_mx other >> than rely on MX's flow control. >> >> Or does Flow (or another upper layer protocol) provide flow control? >> >> Thanks, >> >> Scott >> >> On Jan 5, 2011, at 10:59 AM, Atchley, Scott wrote: >> >>> Hi Phil, >>> >>> Thanks, I'll take a look at it as well. >>> >>> Scott >>> >>> On Jan 5, 2011, at 10:52 AM, Phil Carns wrote: >>> >>>> Hi Scott, >>>> >>>> I'm afraid so. The pvfs2 source tree also still has an old design >>>> document in doc/design/bmi-design.tex. >>>> >>>> -Phil >>>> >>>> On 01/04/2011 03:09 PM, Atchley, Edward S. wrote: >>>>> Hi all, >>>>> >>>>> Is this still the only BMI paper? >>>>> >>>>> BMI: A Network Abstraction Layer for Parallel I/O >>>>> >>>>> Scott >>>>> >>>>> _______________________________________________ >>>>> Pvfs2-users mailing list >>>>> [email protected] >>>>> http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users >>>> _______________________________________________ >>>> Pvfs2-users mailing list >>>> [email protected] >>>> http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users >>> >>> _______________________________________________ >>> Pvfs2-users mailing list >>> [email protected] >>> http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users > _______________________________________________ Pvfs2-users mailing list [email protected] http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users
