Damn the DC did use the wrong type, the worktodo was not wrong I guess gpuowl can only do type 4. Can anyone point me in the direction of a DC with type 4 exponent to grab? Don;t think the DB can be searched by type and the recent results are all type 5 or 1.

[QUOTE=M344587487;511994]Damn the DC did use the wrong type, the worktodo was not wrong I guess gpuowl can only do type 4. Can anyone point me in the direction of a DC with type 4 exponent to grab? Don;t think the DB can be searched by type and the recent results are all type 5 or 1.[/QUOTE]The PRP residue type depends on the version of gpuowl you run. To verify quickly you have the right version of gpuowl for the desired residue type, run a small exponent such as 1257787. For example, V3.8 gpuowl does type 1 PRP residue. Exponent details at mersenne.org will show what residue type the first run was done with; [URL]https://www.mersenne.org/report_exponent/?exp_lo=84000000&exp_hi=84100000&full=1[/URL].
Additionally verify the shift was not zero. Gpuowl does zero shift only, so is not a good DC for a zero shift first test, and a triple check would follow. See also [URL]http://www.mersenne.ca/exponent/84004321[/URL] which does not indicate residue type there.
Zero shift first PRP tests should be DC by prime95 not gpuowl, to ensure a nonzero DC. See [COLOR=Black]84006781.[/COLOR]

Thanks, I was lazy researching but would never have figured to use v3.8.

[QUOTE=M344587487;512009]Thanks, I was lazy researching but would never have figured to use v3.8.[/QUOTE]If you want to qualify your modification or gpu, you could try
[url]https://www.mersenne.org/report_exponent/?exp_lo=84102691&full=1[/url]. Since I ran it, I have a list of interim residues a short run could be checked against.

In some cases gpuowl fails on radeon VII
 

It was with the wrong set of system software, not enough up to date, gpuowl started but after a while the residue was zeroed out, and a page fault occurred.


After installing the latest kernel, modules and headers, v. 5.0, then gpuowl works without problems and the zero-residue error is gone.

[QUOTE=SELROC;512276]It was with the wrong set of system software, not enough up to date, gpuowl started but after a while the residue was zeroed out, and a page fault occurred.


After installing the latest kernel, modules and headers, v. 5.0, then gpuowl works without problems and the zero-residue error is gone.[/QUOTE]




The same error has occurred again, zero-residue, but this time gpuowl reloaded the last checkpoint and continued.


I found that I was running a version of openowl compiled against old libs. Now I have recompiled and waiting to see if the error occurs again.

[QUOTE=kriesel;512010]If you want to qualify your modification or gpu, you could try
[URL]https://www.mersenne.org/report_exponent/?exp_lo=84102691&full=1[/URL]. Since I ran it, I have a list of interim residues a short run could be checked against.[/QUOTE]
There's also a table of interim residues for powers of ten iterations for known Mersenne primes, in the attachment of post 5 at [URL]https://www.mersenneforum.org/showthread.php?t=24003[/URL]

gpuowl asymptotic run time scaling
 

I've extended the third attachment at [URL]https://www.mersenneforum.org/showpost.php?p=488535&postcount=2[/URL] to include a plot of the per iteration times on an RX480 gpu for whichever version of gpuowl tested fastest for each fft length. An approximation of the asymptotic scaling of gpuowl is p[SUP]1.078[/SUP] for ms/iter, p[SUP]2.078[/SUP] for exponent run time, from the trend line fit for fft lengths 6M to 144M (exponents 100M<p<2520M). This is close to values obtained for CUDALucas and prime95, ~2.094, and finally provides for gpuowl a scaling above p[SUP]2[/SUP], which is more consistent with expectations of scaling n[SUP]2[/SUP] log n log log n from such reliable sources as Knuth.

[QUOTE=SELROC;512290]The same error has occurred again, zero-residue, but this time gpuowl reloaded the last checkpoint and continued.


I found that I was running a version of openowl compiled against old libs. Now I have recompiled and waiting to see if the error occurs again.[/QUOTE]




After some hour no error. Will see today the continuation.

[QUOTE=M344587487;511994]Damn the DC did use the wrong type, the worktodo was not wrong I guess gpuowl can only do type 4. Can anyone point me in the direction of a DC with type 4 exponent to grab? Don;t think the DB can be searched by type and the recent results are all type 5 or 1.[/QUOTE]
^ TIL... Is there any way at all to lookup exponents that have been done with a specific type?

[QUOTE=M344587487;511994]Damn the DC did use the wrong type, the worktodo was not wrong I guess gpuowl can only do type 4. Can anyone point me in the direction of a DC with type 4 exponent to grab? Don;t think the DB can be searched by type and the recent results are all type 5 or 1.[/QUOTE]

You can find some PRPs that need DC from the following users:

Warning: not all are type 4. There's no way to filter by residue type, although you can click on the "Residue Type" column header to sort by it.

Also, I think gpuOwL only produces residues with shift count zero, so the double check will also have shift count zero, and some might insist that it's not a proper double check unless it's with a different shift count.
[LIST][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=Mihai+Preda&exdchk=1&dispdate=1&B1="]Mihai Preda[/URL][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=Kriesel&exdchk=1&dispdate=1&exbad=1&exfactor=1&B1="]Kriesel[/URL][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=kwe5ykdf&exdchk=1&dispdate=1&exbad=1&exfactor=1&B1="]kwe5ykdf[/URL][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=tServo&exdchk=1&dispdate=1&exbad=1&exfactor=1&B1="]tServo[/URL][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=Franklin+Webber&exdchk=1&dispdate=1&exbad=1&exfactor=1&B1="]Franklin Webber[/URL][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=Xebecer&exdchk=1&dispdate=1&exbad=1&exfactor=1&B1="]Xebecer[/URL][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=xx005fs&exdchk=1&dispdate=1&exbad=1&exfactor=1&B1="]xx005fs[/URL][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=SEL-ROC&exdchk=1&dispdate=1&exbad=1&exfactor=1&B1="]SEL-ROC[/URL][*][URL="https://www.mersenne.org/report_prp/?exp_lo=82000000&exp_hi=999999999&exp_date=&end_date=&user_only=1&user_id=kracker&exdchk=1&dispdate=1&exbad=1&exfactor=1&B1="]kracker[/URL][/LIST]