On Thu, Nov 23, 2017 at 02:41:16PM +0800, Yang Zhong wrote: > Since there are some issues in memory alloc/free machenism > in glibc for little chunk memory, if Qemu frequently > alloc/free little chunk memory, the glibc doesn't alloc > little chunk memory from free list of glibc and still > allocate from OS, which make the heap size bigger and bigger. > > This patch introduce malloc_trim(), which will free heap memory. > > Below are test results from smaps file. > (1)without patch > 55f0783e1000-55f07992a000 rw-p 00000000 00:00 0 [heap] > Size: 21796 kB > Rss: 14260 kB > Pss: 14260 kB > > (2)with patch > 55cc5fadf000-55cc61008000 rw-p 00000000 00:00 0 [heap] > Size: 21668 kB > Rss: 6940 kB > Pss: 6940 kB > > Signed-off-by: Yang Zhong <yang.zh...@intel.com> > --- > configure | 4 ++++ > util/rcu.c | 6 ++++++ > 2 files changed, 10 insertions(+) > > diff --git a/configure b/configure > index 0e856bb..5b463d4 100755 > --- a/configure > +++ b/configure > @@ -6012,6 +6012,10 @@ if test "$opengl" = "yes" ; then > fi > fi > > +if test "$tcmalloc" = "yes" || test "$jemalloc" = "yes" ; then > + echo "CONFIG_NONGLIBMALLOC=y" >> $config_host_mak
malloc(3) is provided by glibc, not glib, so the name CONFIG_NONGLIBMALLOC is confusing. I suggest calling it CONFIG_MALLOC_TRIM instead: # Even if malloc_trim() is available, these non-libc memory allocators # do not support it. if test "$tcmalloc" = "yes" || test "$jemalloc" = "yes" ; then if test "$malloc_trim" = "yes" ; then echo "Disabling malloc_trim with non-libc memory allocator" fi malloc_trim="no" fi if test "$malloc_trim" != "no" ; then cat > $TMPC << EOF #include <malloc.h> int main(void) { malloc_trim(0); return 0; } EOF if compile_prog "" "" ; then malloc_trim="yes" else malloc_trim="no" fi fi ... if test "$malloc_trim" = "yes" ; then echo "CONFIG_MALLOC_TRIM=y" >> $config_host_mak fi Then the code in rcu.c just has to #ifdef CONFIG_MALLOC_TRIM and there's no need for Linux-specific checks. If other operating systems support malloc_trim() then QEMU will use it by default.
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