Hello Petr, Thanks for the fix! Hard to believe that makedumpfile mmap mode on s390 has never worked. On Fri, 27 Feb 2015 13:14:09 +0100 Petr Tesarik <ptesarik at suse.cz> wrote: > Hi all, > > update_mmap_range() expects a file offset as its first argument, but > initialize_mmap() passes a physical address. Since the first segment > usually starts at physical addr 0 on S/390, but there is no segment > at file offset 0, update_mmap_range() fails, and makedumpfile falls > back to read(). And for other architectures the wrong parameter was no problem? > > @Michael: I wonder how you actually tested the kernel mmap patches; > this bug has prevented mmap on all my s390 systems... We tested /proc/vmcore mmap with our SCSI stand-alone dump (zfcpdump) and with small test programs that used mmap. I did a quick test with your patch and it looks like the mmap mode on my s390 system is slower than the read mode: # time ./makedumpfile -d 31 /proc/vmcore out real 0m1.043s user 0m0.187s sys 0m0.433s # time ./makedumpfile -d 31 /proc/vmcore out --non-mmap real 0m0.767s user 0m0.098s sys 0m0.364s We will have to look into this. Michael
