llvm-project/llvm/lib/Support/Unix
David Blaikie 602a5bbb32 Support: Don't set RLIMIT_AS on child processes when applying a memory limit
It doesn't seem relevant to set an address space limit - this isn't
important in any sense that I'm aware & it gets in the way of things
that use a lot of address space, like llvm-symbolizer.

This came up when I realized that bugpoint regression tests were much
slower with -gsplit-dwarf than plain -g. Turned out that bugpoint
subprocesses (opt, etc) were crashing and doing symbolization - but
bugpoint runs those subprocesses with a 400MB memory limit. So with
plain -g, mmaping the opt binary would exceed the memory limit, fail,
and thus be really fast - no symbolization occurred. Whereas with
-gsplit-dwarf, comically, having less to map in, it would succeed and
then spend lots of time symbolizing.

I've fixed at least the critical part of bugpoint's perf problem there
by adding an option to allow bugpoint to disable symbolization. Thus
improving the perfromance for -gsplit-dwarf and making the -g-esque
speed available without this quirk/accidental benefit.

llvm-svn: 305242
2017-06-12 22:16:49 +00:00
..
COM.inc
DynamicLibrary.inc Close DynamicLibraries in reverse order they were opened. 2017-06-05 16:26:58 +00:00
Host.inc
Memory.inc Correct mprotect page boundries to round up end page. Fixes PR30905. 2016-11-05 04:22:15 +00:00
Mutex.inc
Path.inc Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
Process.inc Remove spurious cast of nullptr. NFC. 2017-05-11 08:53:00 +00:00
Program.inc Support: Don't set RLIMIT_AS on child processes when applying a memory limit 2017-06-12 22:16:49 +00:00
README.txt
RWMutex.inc
Signals.inc Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
ThreadLocal.inc Revert "Fix Clang-tidy modernize-deprecated-headers warnings in remaining files; other minor fixes." 2016-04-05 20:45:04 +00:00
Threading.inc Sort the remaining #include lines in include/... and lib/.... 2017-06-06 11:49:48 +00:00
Unix.h Remove TimeValue usage from llvm/Support 2016-10-24 10:59:17 +00:00
Watchdog.inc

README.txt

llvm/lib/Support/Unix README
===========================

This directory provides implementations of the lib/System classes that
are common to two or more variants of UNIX. For example, the directory
structure underneath this directory could look like this:

Unix           - only code that is truly generic to all UNIX platforms
  Posix        - code that is specific to Posix variants of UNIX
  SUS          - code that is specific to the Single Unix Specification
  SysV         - code that is specific to System V variants of UNIX

As a rule, only those directories actually needing to be created should be
created. Also, further subdirectories could be created to reflect versions of
the various standards. For example, under SUS there could be v1, v2, and v3
subdirectories to reflect the three major versions of SUS.