On Mon, 12 Dec 2011 15:29:07 +0100, Mel Gorman mel@csn.ul.ie wrote:
On Fri, Nov 18, 2011 at 05:43:11PM +0100, Marek Szyprowski wrote:
From: Michal Nazarewicz mina86@mina86.com
This commit exports some of the functions from compaction.c file outside of it adding their declaration into internal.h header file so that other mm related code can use them.
This forced compaction.c to always be compiled (as opposed to being compiled only if CONFIG_COMPACTION is defined) but as to avoid introducing code that user did not ask for, part of the compaction.c is now wrapped in on #ifdef.
Signed-off-by: Michal Nazarewicz mina86@mina86.com Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com
mm/Makefile | 3 +- mm/compaction.c | 112 +++++++++++++++++++++++-------------------------------- mm/internal.h | 35 +++++++++++++++++ 3 files changed, 83 insertions(+), 67 deletions(-)
diff --git a/mm/Makefile b/mm/Makefile index 50ec00e..24ed801 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -13,7 +13,7 @@ obj-y := filemap.o mempool.o oom_kill.o fadvise.o \ readahead.o swap.o truncate.o vmscan.o shmem.o \ prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \ page_isolation.o mm_init.o mmu_context.o percpu.o \
$(mmu-y)
$(mmu-y) compaction.oThat should be
compaction.o $(mmu-y)
for consistency.
Overall, this patch implies that CMA is always compiled in.
Not really. But yes, it produces some bloat when neither CMA nor compaction are compiled. I assume that linker will be able to deal with that (since the functions are not EXPORT_SYMBOL'ed).
Note also that the was majority of compaction.c is #ifdef'd though so only a handful of functions are compiled.
Why not just make CMA depend on COMPACTION to keep things simplier?
I could imagine that someone would want to have CMA but not compaction, hence I decided to give that choice.
For example, if you enable CMA and do not enable COMPACTION, you lose things like the vmstat counters that can aid debugging. In fact, as parts of compaction.c are using defines like COMPACTBLOCKS, I'm not even sure compaction.c can compile without CONFIG_COMPACTION because of the vmstat stuff.