Some more info on my delima.
I did an strace with.
strace sks build ./dump/*.pgp -n 10 -cache 100
I let it run till it stalled and it ended with :
gettimeofday({1302360337, 140336}, NULL) = 0
gettimeofday({1302360337, 140434}, NULL) = 0
mmap2(NULL, 1089536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f937000
pread64(5, "\0\0\0\0\1\0\0\0\1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\10\1\5\0\0\0\0\0\0"..., 2048, 2048) = 2048
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f8b9000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f83b000
mmap2(NULL, 954368, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f752000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f6d4000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f656000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f5d8000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f55a000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f4dc000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f45e000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f3e0000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f362000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f2e4000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f266000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x8f1e8000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f16a000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f0ec000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8f06e000
mmap2(NULL, 516096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x8eff0000
sched_yield() = 0
futex(0xb71792c8, FUTEX_WAIT, 1, NULL