----- Original Message ----- From: "Brian J. Beesley" <[EMAIL PROTECTED]> To: "Daran" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; "Anurag Garg" <[EMAIL PROTECTED]> Sent: Tuesday, June 11, 2002 8:23 PM Subject: Re: Mersenne: P-1 Puzzle
> On Tuesday 11 June 2002 06:13, Daran wrote: > > [... snip ... interesting but non-contentious] > > > Very noticable is the proportion of exponents - in all three ranges - > > which are not getting a stage two effort at all. 26 out the 85 exponents > > between 7950000 and 796000, 24 out of 54 between 15500000 and > > 15505000, 35 out of 57 between 33219000 and 33223000. I do not > > believe that large numbers of P4 systems are being shipped with just > > 8MB of RAM! > > This is true. However the philosophy of the project, correctly in my view, > is that the software should not cause noticeable deterioration in the > performance of a system when it is being run in the background to normal > work. I agree. My remarks were intended to make the case for spinning P-1 off into a separate work type, (yeah, I know, it's difficult to change the server code), and to encourage other readers of this list to consider focussing on P-1 work. [...] > The default has to be "safe";... Again, I agree. While there will be some people who have made a deliberate decision not to allocate extra memory, in many cases people will simply have accepted the default, which means that some machines which could allocate more memory to stage 2 without adversely affecting the user won't be configured to do this. However that same tendency to accept defaults puts GIMPS programmers under an obligation to set those defaults conservatively. > ...IMO the current default memory allowance of 8MB > is entirely reasonable, even though it causes P-1 to run stage 1 only for > any realistic assignment, and even though _new_ systems are usually delivered > with at least 256 MB RAM. Against that is the observation that the basic memory footprint has barely changed in the over three years I've been with the project, while typical system memory has increased by a factor of four or more. A default set to 10% of available memory would allow a 256MB system to perform a modest stage 2 on low assignments in the test range, and on DC assignments, while still using proportionately less memory than three years ago. The effect of this could be further mitigated if the memory dialog included radio buttons to limit further the memory usage to 'minimum' (default), with other options being 'reasonable' and 'desireable', (as described in the helpfile) as well as 'maximum', and 'Do not run'. Thus the default would be to run a minimal stage 2 provided it could be done in 10% of system memory or less. I would consider this to be reasonable and conservative. > Running P-1 on a "10 million digit" exponent requires in excess of 64 MB > memory to be allocated in order to run stage 2 at all. That's a lot to ask > as a default! It is. OTOH if the box has 1GB installed, then it's not so much. > Regards > Brian Beesley Daran _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
