On Sunday 19 September 2010 23:07:09 Nikanth Karthikesan wrote: > On Wednesday 15 September 2010 19:44:17 Richard Guenther wrote: > > On Wed, 15 Sep 2010, Balbir Singh wrote: > > > * Nikanth Karthikesan <knikanth@xxxxxxx> [2010-09-15 12:01:11]: > > > > How? Current smaps information without this patch provides incorrect > > > > information. Just because a private dirty page became part of swap > > > > cache, it shown as clean and backed by a file. If it is shown as > > > > clean and backed by swap then it is fine. > > > > > > How is GDB using this information? > > > > GDB counts the number of dirty and swapped pages in a private mapping and > > based on that decides whether it needs to dump it to a core file or not. > > If there are no dirty or swapped pages gdb assumes it can reconstruct > > the mapping from the original backing file. This way for example > > shared libraries do not end up in the core file. > > Well, may be /proc/pid/pagemap + /proc/kpageflags is enough for this! One > can get the pageflags using these interfaces. See > Documentation/vm/pagemap.txt for the explanation on how to do it. There is > also a sample program that prints page flags using this interface in > Documentation/vm/page-types.c. > > It is bad that /proc/pid/pagemap is never mentioned in > Documentation/filesystems/proc.txt. I will send a patch to rectify this. Or even simpler, /proc/pid/numa_maps already exports the number of anonymous pages in a mapping, if you have CONFIG_NUMA=y! Again not documented in Documentation/filesystems/proc.txt Thanks Nikanth -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>