Messages in this thread | | | Date | Sat, 10 Aug 2002 14:12:01 +0200 | From | Richard Zidlicky <> | Subject | Re: mmapping large files hits swap in 2.4? |
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On Fri, Aug 09, 2002 at 07:26:14PM +0200, Daniel Egger wrote: > Hija, > > I'm currently looking into optimizing GIMPs own swapping algorithm > by replacing naive file operations by mmap-based ones. Unfortunately > my test machine (PPC, 256MB) gets hit really hard by mmapping files over > 100MB into memory: The swap utilization grows up to the file size > and the machine is completely unresponsive for several seconds up to > a few minutes. Seemingly the writes to the mmaped area first hit the > swap and then are read from there again to fit the designated file. > > I'm doing something along the lines of: > area = mmap (0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
seems like you are doing something else, like hitting all of the file.
# uname -a Linux sirizidl.dialin.rrze.uni-erlangen.de 2.4.18 #27 Wed Jul 24 17:25:39 CEST 2002 m68k unknown
main() { char *area; int fd=open("/msrc/linux/distr/cd.image", O_RDWR); area = mmap (0, 168088*4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (area == -1) perror("mmap"); }
# time ./mmap real 0m0.035s user 0m0.020s sys 0m0.020s
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