Why not use smaller packets? Was: RE: [RC5] client versions - AIX

Bruce Wilson bwilson at distributed.net
Thu Oct 3 09:59:12 EDT 2002


JackB,

It seems clear that no matter how well I explain the reasons for why we
do things a given way, you refuse to see it from _our_ side.  In fact,
your responses suggest that you barely understand my points at all.
Nonetheless, I will try again to correct the errors in your points, and
explain why we cannot make the changes you propose.

*  The proxy is the proxy, the client is the client.  They are
fundamentally different in huge ways.  Turning the proxy into a
"superclient" is problematic in many ways.  The changes you propose
require a huge increase in complexity in both the client and proxy.
This would require a lot of coding, with a huge potential for creating
new problems.

*  The decision has already been made that RC5-72 will not in any way
work with units smaller than 2^32.  Some of us pushed for a larger
minimum, including me.  You will get no sympathy from me in your pleas
for a smaller workunit.  Also, checkpoints do not subdivide by 2^28,
they save to disk based on an amount of time.

*  It is very possible for work obtained from a perproxy to be returned
directly to our network without going through the perproxy.  (See config
option 2 -> 6 -> 5, "Disable fallback to a distributed.net keyserver?"
which defaults to "no", which means "allow fallback").  The work can
also be returned to a different perproxy.  If we build anything that
assumes the perproxy will get back all the work it gives out, it will
cause a lot of perfectly good work to be dropped on the floor.

*  For better or worse, perproxies are not under our control, so we
cannot trust that they will not be mismanaged, or even that they will be
upgraded.  Currently, the only way to start telling certain versions of
dnetc that a project is closed is to distribute new perproxies.  We know
from repeated experience that not all upgrades will take place -- we're
still receiving work from clients working on DES and RC5-56.

All the ideas you have mentioned here and in previous conversations HAVE
BEEN CONSIDERED, often before you mentioned them.  The common thread in
these ideas is they violate the fundamental concepts underlying our
network, require large amounts of complex coding, and run contrary to
our goals as an organization.

As an organization, we cannot afford to write the clients and proxies to
support a given niche of users like you.  We instead must develop the
clients and proxies to work in as many varied scenarios as possible.
This includes not only different network topologies (proxy, no proxy,
sneakernet), but different corporate policies (e.g. "you can run the
proxy on the firewall, but not the client"), different user environments
(some users want it running in front, others as an icon in the system
tray, some run it as a service, some only when the screensaver is on),
different installation scenarios (some users install it and forget it,
others configure it to the hilt), and different philosophies (choice of
projects, co-existing with another distributed computing project).

Bottom line, if a feature won't support all these scenarios and more I
haven't mentioned, it's not in our best interest to add it to the
client.


__
Bruce Wilson <bwilson at distributed.net>
PGP KeyID: 5430B995, http://www.toomuchblue.com/ 

Build a man a fire and he'll be warm for a day.
Set a man on fire, he'll be warm for the rest of his life.




| -----Original Message-----
| From: owner-rc5 at lists.distributed.net 
| [mailto:owner-rc5 at lists.distributed.net] On Behalf Of Jack Beglinger
| Sent: Wednesday, October 02, 2002 22:47
| To: rc5 at lists.distributed.net
| Subject: Why not use smaller packets? Was: RE: [RC5] client 
| versions - AIX
| 
| 
| > You may be disappointed with RC5-72.  Based on the success 
| of the longer
| > workunits in the OGR projects, we are scaling the RC5-72 
| workunits to a
| > larger size.  It is very possible that you may get RC5-72 
| workunits that
| > take much longer than they did with RC5-64.
| 
| Great - DNET use larger blocks!! But why have the personal 
| proxy have to 
| hand the larger ones too?  There is no need, if you make it a 
| super "client".
| 
| > Changing the minimum from 2^28 to 2^32 means that the 
| smallest workunit
| > under RC5-72 will take 16 times longer to process than the smallest
| > workunit for RC5-64.  A slow machine that used to do a 2^28 
| in two hours
| > will now take 32 hours to finish a workunit for RC5-72.  
| This workunit
| > would also earn 16 times as much stats credit, just as if 
| it had done 16
| > workunits of 2^28.
| 
| You are great with math... but lets see - you will give us 
| create at the 2^28 
| reference point but refuse to give out the block in smaller 
| than 2^32....  It 
| seams you are wasting a lot of processing space and time for 
| work you will 
| not be supporting....  Not a good use of resources, unless 
| you are willing to 
| allow for sub sections to be processed in units that match 
| the 2^28 size.
| 
| > A workunit of 2^36 would take 256 times longer, and 2^40 
| (if we offer
| > them) would take 4096 times longer.  With proper 
| checkpointing in place,
| > this is no problem.  I plan on using the largest workunit 
| available as
| 
| Check pointing IS sub blocks.  YOu are already setup the 
| clients to handle 
| smaller work points -- use the similar or even same logic in 
| both client and 
| personal proxy to handle smaller units.
| 
| Oh, you are worried that smaller unit will come back to DNET. 
|  If you read 
| my first note... the personal is responsible to return only 
| whole completed 
| blocks.  If a part is missing... it would get a client to 
| reprocess it and get the 
| block back.  Just like a client that is working on a block 
| and gets stop... the 
| check point is used to help it get back on track and return a 
| completed block.
| 
| > The fullproxies do receive larger "superblocks".  I'm not 
| sure of the
| > size, but they are significantly larger.  Perproxies don't receive
| > superblocks because (a) superblocks are only available 
| directly from the
| > keymaster, and (b) there is too much potential for abuse. 
| 
| You have the same abuse now.  The way you filter is watch for 
| high return 
| rates, and check out what is happening.  The same would go 
| for this, it is no 
| different.
| 
| > The problem is, the smaller we allow the workunit to be 
| subdivided, the
| > more details we need to track at the keymaster.  It's not a safe
| > assumption that work handed out by a perproxy will be 
| returned to the
| > same proxy to be recombined.  Even if they do come back to the same
| > place, there could be enough of a delay to increase the storage
| > requirement of the proxy, and to delay credit to those who 
| turned it in
| > first.  If I do half of a workunit, and the other half gets 
| deleted from
| > someone's buff-in, I might never get credit at all!
| 
| No it is not a problem, unless you make it into one.  
| Subdividing work units 
| into a useable size for a local network and having the be 
| processed by many 
| small "hands" and assembled and return to the key server in 
| the sky... The 
| key server would be no wiser.  It gave out a block and 
| returned a block - why 
| would it care which branch of a multiple threaded processor 
| is working on the 
| packet.  The question is... is it done right.
| 
| > It's impractical to use smaller units at the clients than 
| we track at
| > the keymaster.  If a perproxy splits a 2^32 16 ways to 16 different
| > clients, then who gets stats credit for the finished 2^32?
| 
| Again the keymaster would not be handling the small packets - 
| that is the 
| personal proxy.  
| 
| And to answer your question...  Allow the proxy to either one:
| 
| 1) Be configured return the user, machine type, os type 
| (including mixed & 
| mixed)  - this way the personal proxy for small packets would 
| be the "client" 
| to DNET.  Also the only way to configure a small packet 
| client is to have a 
| personal proxy.
| 
| 2) Allow the proxy to return two types if information with a 
| key packet....
| The packet completion and the stats break down so multiple 
| machines or 
| users or ... will be preprocessed ready to add to the stats 
| boxs.  With that 
| added in would make it easier for teams to keep their own 
| stats... because 
| the personal proxies is giving them out.
| 
| > In the final calculation, it takes just as long to do a 
| single 2^32 as
| > it does to do 16 2^28's, and the stats credits are the 
| same, so why make
| > a big deal of it?  Most distributed projects give you no control
| > whatsoever of the size workunit you want.  We've considered 
| this option
| > too, specifically because it makes discussions like this moot.
| 
| You are right the time to process a 2^32 is the same as 
| processing 16 2^28, 
| EXCEPT...
|   1) processing in parallel so the "machine" appears to 
| crunch that 2^32 16 
| times faster.
|   2) I am not wasting time for the CPU to control an IDE 
| drive while check 
| pointing.
|   3) I am using less power and creating less heat by not 
| having excess 
| circuitry running.
|  
| > The clients already take responsibility for picking their 
| own randoms.
| > It doesn't make sense to shift this to the perproxies, because the
| > client still needs to generate randoms if it can't reach 
| the perproxy.
| 
| That is right that is a backup...  the client generates it 
| own random number.  
| Which I have found when I had a cable break 3 days... they 
| are not that 
| random for a client or for the network of machines.  
| 
| If the break is outside of firewall/personal proxy.  Allow 
| the proxy to makeup 
| random BIG BLOCKS and hand out smaller work units... again... the 
| Keymaster in the sky will get only large blocks  -- maybe 
| even every large 
| random blocks.  The clients are not trying to guess a random 
| block and 
| having overlap because the number of machine processing random blocks 
| are the same time ( and in the a very small sub space)
| 
| > Each workunit returned must be ticked off as "completed" in the
| > keymaster.  It doesn't make sense to have the proxies send back a
| > summary when we still need all the detail.  We have also implemented
| > mechanisms in the past where work from certain client versions are
| > discarded at the master.  If a proxy combines work from 10 computers
| > using the same ID but different versions and platforms, we lose the
| > ability to filter out the noise.  This also makes the 
| perproxies much
| > more complicated, which makes the code much harder to modify and
| > maintain.
| 
| Try looking from my side -- it does not make since to have 
| the keyservers 
| and stats server working all the time on small things (even 
| 2^32 is a small 
| thing!).  Why not find away to have the DISTRIBUTED.NET 
| "super" machine 
| distribute more of the work so like maybe... Real Time stats 
| could come to 
| be.  
| 
| To filter out the "noise" close the projects to client types 
| - like you close 
| projects.  This why you can disable bad clients or proxies 
| and get the load 
| off servers but preventing the connections.  
| 
| To solve the version issue... only allow a block being 
| handled by a personal 
| proxy to be worked on by a single version of the client, 
| maybe even os and 
| cpu... but I do not see that level of need.  Have one of the 
| stats of the 
| personal proxy showing the number of different blocks it is 
| having to support, 
| so the user would get the versions n'sync.
|  
| > We like the proxies as waypoints, merely passing work from 
| here to there
| > without knowing much about what is inside each workunit.  
| This makes it
| > easier for our network to support new projects without a 
| lot of changes.
| 
| The proxies can also be viewed as clients without a 
| crunchers.   And clients 
| can be viewed as proxies with crunchers.  You have people who have 
| multiple clients sharing a common buffers.  Even the SMP 
| machines run one 
| client per processor.   Some work and all could be one.  So on a SMP 
| machine one becomes the master and others check work in/out with it.
| 
| Please step out of the box and look around, there are more 
| than one way to 
| see the issues.  
| 
| jackb
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