On Wed, 2 Feb 2000, Jamie Lokier wrote:
> Chuck Lever wrote:
> > this is exactly what an interface like mincore() is designed for. the
> > application, or an underlying threads library, can use it to avoid page
> > faults that would block all the threads running in an address space.
>
> You want to read part of one of your mmap()ed files. How do you check
> if it's going to fault?
usually like this:
int fd;
void * map;
char vec[VEC_SIZE];
fd = open("/your/file, O_RDONLY);
if (fd == -1) {
perror("open");
exit(-1);
}
map = mmap(0, SIZE, PROT_READ, MAP_PRIVATE, fd, 0);
if (!map) {
perror("mmap");
close(fd);
exit(-1);
}
if (mincore(map, readlength, vec))
perror("mincore");
the vec[] contains a byte for each page you queried. each byte has value
"1" if the page is already in memory, otherwise "0".
- Chuck Lever
-- corporate: <chuckl@netscape.com> personal: <chucklever@netscape.net> or <cel@monkey.org>The Linux Scalability project: http://www.citi.umich.edu/projects/linux-scalability/
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This archive was generated by hypermail 2b29 : Mon Feb 07 2000 - 21:00:08 EST