yafu/factor/nfs/nfs_sieving.c:283

            // edit lbpr/a depending on test results.  we target something around 2 rels/Q.
            // could also change siever version in more extreme cases.
            if (count > 4*actual_range)
            {
                if (VFLAG > 0)
                    printf("test: yield greater than 4x/spq, reducing lpbr/lpba\n");
                jobs[i].lpba--;
                jobs[i].lpbr--;
                jobs[i].mfba -= 2;
                jobs[i].mfbr -= 2;
            }

            if (count > 8*actual_range)
            {
                char *pos;
                int siever;

                pos = strstr(jobs[i].sievername, "gnfs-lasieve4I");
                siever = (pos[14] - 48) * 10 + (pos[15] - 48);

                if (VFLAG > 0)
                    printf("test: yield greater than 8x/spq, reducing siever version\n");

                switch (siever)
                {
                case 11:
                    if (VFLAG > 0) printf("test: siever version cannot be decreased further\n");
                    jobs[i].snfs->siever = 11;
                    break;

                case 12:
                    pos[15] = '1';
                    jobs[i].snfs->siever = 11;
                    break;

                case 13:
                    pos[15] = '2';
                    jobs[i].snfs->siever = 12;
                    break;

                case 14:
                    pos[15] = '3';
                    jobs[i].snfs->siever = 13;
                    break;

                case 15:
                    pos[15] = '4';
                    jobs[i].snfs->siever = 14;
                    break;

                case 16:
                    pos[15] = '5';
                    jobs[i].snfs->siever = 15;
                    break;
                }
            }

            if (count < actual_range)
            {
                if (VFLAG > 0)
                    printf("test: yield less than 1x/spq, increasing lpbr/lpba\n");

                jobs[i].lpba++;
                jobs[i].lpbr++;
                jobs[i].mfba += 2;
                jobs[i].mfbr += 2;
            }

            if (count < (actual_range/2))
            {
                char *pos;
                int siever;

                pos = strstr(jobs[i].sievername, "gnfs-lasieve4I");
                siever = (pos[14] - 48) * 10 + (pos[15] - 48);

                if (VFLAG > 0)
                    printf("test: yield less than 1x/2*spq, increasing siever version\n");

                switch (siever)
                {
                case 16:
                    if (VFLAG > 0) printf("test: siever version cannot be increased further\n");
                    jobs[i].snfs->siever = 16;
                    break;

                case 15:
                    pos[15] = '6';
                    jobs[i].snfs->siever = 16;
                    break;

                case 14:
                    pos[15] = '5';
                    jobs[i].snfs->siever = 15;
                    break;

                case 13:
                    pos[15] = '4';
                    jobs[i].snfs->siever = 14;
                    break;

                case 12:
                    pos[15] = '3';
                    jobs[i].snfs->siever = 13;
                    break;

                case 11:
                    pos[15] = '2';
                    jobs[i].snfs->siever = 12;
                    break;
                }
            }