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I've meet a strange behavior with these commands on my gentoo box: 1: perf kmem record 2: CTRL-C to stop 1 3: perf report 4: "Enter", "Enter", "Run scripts for all samples", "event_analyzing_sample". Then 'perf report' says: " No kallsyms or vmlinux with build-id xxxx was found /lib/modules/4.10.0+/build/vmlinux with build id xxxx not found, continuing without symbols ". It is strange because I am sure /lib/modules/4.10.0+/build/vmlinux is right for perf.data. After digging, I found out the reason is that "perf report" generates many open fds, then "script_browse" uses popen to run "perf script" which run out of open files. The gentoo box has a small default value for "max open files", 1024. Yes, "ulimit -n " with a bigger number could fix it, but I think that using O_CLOEXEC in do_open is a better way. Signed-off-by: Wang YanQing <udknight@gmail.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20180115050448.GA20759@udknight [ Make sure O_CLOEXEC is available in old systems by adding a patch just before this one, to keep this bisectable in such systems ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.