Hello,
From: iamjoonsoo.kim@lge.com To: pintu_agarwal@yahoo.com; linux-mm@kvack.org; linux-arm-kernel@lists.infradead.org; linaro-mm-sig@lists.linaro.org; ritesh.list@gmail.com CC: pintu.k@outlook.com; pintu.k@samsung.com; vishu_1385@yahoo.com; m.szyprowski@samsung.com; mina86@mina86.com; ngupta@vflare.org; iqbalblr@gmail.com Subject: RE: [linux-3.10.17] Could not allocate memory from free CMA areas Date: Mon, 4 Aug 2014 16:11:00 +0900
Dear Joonsoo,
I tried your changes which are present at the below link. https://github.com/JoonsooKim/linux/tree/cma-fix-up-v3.0-next-20140625 But unfortunately for me it did not help much. After running various apps that uses ION nonmovable memory, it fails to allocate memory after some time. When I see the pagetypeinfo shows lots of CMA pages available and non-movable were very less and thus nonmovable allocation were failing.
Okay. CMA pages cannot be used for nonmovable memory, so it can fail in above case.
However I noticed the failure was little delayed.
It is good sign. I guess that there is movable/CMA ratio problem. My patchset uses free CMA pages in certain ratio to free movable page consumption. If your system doesn't use movable page sufficiently, free CMA pages cannot be used fully. Could you test with following workaround?
if (normal> cma) {zone->max_try_normal = pageblock_nr_pages;zone->max_try_cma = pageblock_nr_pages;} else {zone->max_try_normal = pageblock_nr_pages;zone->max_try_cma = pageblock_nr_pages;}
I applied these changes but still the allocations are failing because there are no non-movable memory left in the system. With the changes I noticed that nr_cma_free sometimes becomes almost zero. But in our case Display/Xorg needs to have atleast 8MB of CMA (contiguous) memory of order-8 and order-4 type. CMA:56MB is shared across display,camera,video etc.
I think the previous changes are slightly better.
My concern is that whether I am applying all you changes or missing some thing. I saw that your kernel version is based on next-20140625 but my kernel version is 3.10.17. And till now I applied only the below changes: https://github.com/JoonsooKim/linux/commit/33a0416b3ac1cd7c88e6b35ee61b4a81a...
But I haven't applied this: https://github.com/JoonsooKim/linux/commit/166b4186d101b190cf50195d841e2189f... (CMA: always treat free cma pages as non-free on watermark checking) These changes have other dependencies which is not present in my kernel version. Like inclusion of ALLOC_FAIR and area->nr_cma_free. Please let me know if these changes are also important for "aggressive alloc changes..."
If possible please send me all the patches related to "aggressive cma.." so that I can conclude on my experiment.
Further I will share the experimental result from my side.
Thanks.