Messages in this thread | | | Subject | Re: [PATCH] mm/swap: add function get_total_swap_pages to expose total_swap_pages | From | Christian König <> | Date | Fri, 2 Feb 2018 08:46:07 +0100 |
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Can you try to use a fixed limit like I suggested once more?
E.g. just stop swapping if get_nr_swap_pages() < 256MB.
Regards, Christian.
Am 02.02.2018 um 07:57 schrieb He, Roger: > Use the limit as total ram*1/2 seems work very well. > No OOM although swap disk reaches full at peak for piglit test. > > But for this approach, David noticed that has an obvious defect. > For example, if the platform has 32G system memory, 8G swap disk. > 1/2 * ram = 16G which is bigger than swap disk, so no swap for TTM is allowed at all. > For now we work out an improved version based on get_nr_swap_pages(). > Going to send out later. > > Thanks > Roger(Hongbo.He) > -----Original Message----- > From: He, Roger > Sent: Thursday, February 01, 2018 4:03 PM > To: Koenig, Christian <Christian.Koenig@amd.com>; Zhou, David(ChunMing) <David1.Zhou@amd.com>; dri-devel@lists.freedesktop.org > Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org; 'He, Roger' <Hongbo.He@amd.com> > Subject: RE: [PATCH] mm/swap: add function get_total_swap_pages to expose total_swap_pages > > Just now, I tried with fixed limit. But not work always. > For example: set the limit as 4GB on my platform with 8GB system memory, it can pass. > But when run with platform with 16GB system memory, it failed since OOM. > > And I guess it also depends on app's behavior. > I mean some apps make OS to use more swap space as well. > > Thanks > Roger(Hongbo.He) > -----Original Message----- > From: dri-devel [mailto:dri-devel-bounces@lists.freedesktop.org] On Behalf Of He, Roger > Sent: Thursday, February 01, 2018 1:48 PM > To: Koenig, Christian <Christian.Koenig@amd.com>; Zhou, David(ChunMing) <David1.Zhou@amd.com>; dri-devel@lists.freedesktop.org > Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org > Subject: RE: [PATCH] mm/swap: add function get_total_swap_pages to expose total_swap_pages > > But what we could do is to rely on a fixed limit like the Intel driver does and I suggested before. > E.g. don't copy anything into a shmemfile when there is only x MB of swap space left. > > Here I think we can do it further, let the limit value scaling with total system memory. > For example: total system memory * 1/2. > If that it will match the platform configuration better. > > Roger can you test that approach once more with your fix for the OOM issues in the page fault handler? > > Sure. Use the limit as total ram*1/2 seems work very well. > No OOM although swap disk reaches full at peak for piglit test. > I speculate this case happens but no OOM because: > > a. run a while, swap disk be used close to 1/2* total size and but not over 1/2 * total. > b. all subsequent swapped pages stay in system memory until no space there. > Then the swapped pages in shmem be flushed into swap disk. And probably OS also need some swap space. > For this case, it is easy to get full for swap disk. > c. but because now free swap size < 1/2 * total, so no swap out happen after that. > And at least 1/4* system memory will left because below check in ttm_mem_global_reserve will ensure that. > if (zone->used_mem > limit) > goto out_unlock; > > Thanks > Roger(Hongbo.He) > -----Original Message----- > From: Koenig, Christian > Sent: Wednesday, January 31, 2018 4:13 PM > To: He, Roger <Hongbo.He@amd.com>; Zhou, David(ChunMing) <David1.Zhou@amd.com>; dri-devel@lists.freedesktop.org > Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH] mm/swap: add function get_total_swap_pages to expose total_swap_pages > > Yeah, indeed. But what we could do is to rely on a fixed limit like the Intel driver does and I suggested before. > > E.g. don't copy anything into a shmemfile when there is only x MB of swap space left. > > Roger can you test that approach once more with your fix for the OOM issues in the page fault handler? > > Thanks, > Christian. > > Am 31.01.2018 um 09:08 schrieb He, Roger: >> I think this patch isn't need at all. You can directly read total_swap_pages variable in TTM. >> >> Because the variable is not exported by EXPORT_SYMBOL_GPL. So direct using will result in: >> "WARNING: "total_swap_pages" [drivers/gpu/drm/ttm/ttm.ko] undefined!". >> >> Thanks >> Roger(Hongbo.He) >> -----Original Message----- >> From: dri-devel [mailto:dri-devel-bounces@lists.freedesktop.org] On >> Behalf Of Chunming Zhou >> Sent: Wednesday, January 31, 2018 3:15 PM >> To: He, Roger <Hongbo.He@amd.com>; dri-devel@lists.freedesktop.org >> Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org; Koenig, >> Christian <Christian.Koenig@amd.com> >> Subject: Re: [PATCH] mm/swap: add function get_total_swap_pages to >> expose total_swap_pages >> >> Hi Roger, >> >> I think this patch isn't need at all. You can directly read total_swap_pages variable in TTM. See the comment: >> >> /* protected with swap_lock. reading in vm_swap_full() doesn't need >> lock */ long total_swap_pages; >> >> there are many places using it directly, you just couldn't change its value. Reading it doesn't need lock. >> >> >> Regards, >> >> David Zhou >> >> >> On 2018年01月29日 16:29, Roger He wrote: >>> ttm module needs it to determine its internal parameter setting. >>> >>> Signed-off-by: Roger He <Hongbo.He@amd.com> >>> --- >>> include/linux/swap.h | 6 ++++++ >>> mm/swapfile.c | 15 +++++++++++++++ >>> 2 files changed, 21 insertions(+) >>> >>> diff --git a/include/linux/swap.h b/include/linux/swap.h index >>> c2b8128..708d66f 100644 >>> --- a/include/linux/swap.h >>> +++ b/include/linux/swap.h >>> @@ -484,6 +484,7 @@ extern int try_to_free_swap(struct page *); >>> struct backing_dev_info; >>> extern int init_swap_address_space(unsigned int type, unsigned long nr_pages); >>> extern void exit_swap_address_space(unsigned int type); >>> +extern long get_total_swap_pages(void); >>> >>> #else /* CONFIG_SWAP */ >>> >>> @@ -516,6 +517,11 @@ static inline void show_swap_cache_info(void) >>> { >>> } >>> >>> +long get_total_swap_pages(void) >>> +{ >>> + return 0; >>> +} >>> + >>> #define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));}) >>> #define swapcache_prepare(e) ({(is_migration_entry(e) || >>> is_device_private_entry(e));}) >>> >>> diff --git a/mm/swapfile.c b/mm/swapfile.c index 3074b02..a0062eb >>> 100644 >>> --- a/mm/swapfile.c >>> +++ b/mm/swapfile.c >>> @@ -98,6 +98,21 @@ static atomic_t proc_poll_event = ATOMIC_INIT(0); >>> >>> atomic_t nr_rotate_swap = ATOMIC_INIT(0); >>> >>> +/* >>> + * expose this value for others use >>> + */ >>> +long get_total_swap_pages(void) >>> +{ >>> + long ret; >>> + >>> + spin_lock(&swap_lock); >>> + ret = total_swap_pages; >>> + spin_unlock(&swap_lock); >>> + >>> + return ret; >>> +} >>> +EXPORT_SYMBOL_GPL(get_total_swap_pages); >>> + >>> static inline unsigned char swap_count(unsigned char ent) >>> { >>> return ent & ~SWAP_HAS_CACHE; /* may include SWAP_HAS_CONT flag */ >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
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