[Intel-gfx] [PATCH RESEND v3 2/3] drm/ttm: Reduce the number of used allocation orders for TTM pages
Daniel Vetter
daniel at ffwll.ch
Wed Apr 12 09:08:11 UTC 2023
On Tue, 11 Apr 2023 at 15:45, Daniel Vetter <daniel at ffwll.ch> wrote:
>
> On Tue, Apr 11, 2023 at 02:11:18PM +0200, Christian König wrote:
> > Am 11.04.23 um 11:51 schrieb Daniel Vetter:
> > > On Tue, Apr 04, 2023 at 10:06:49PM +0200, Thomas Hellström wrote:
> > > > When swapping out, we will split multi-order pages both in order to
> > > > move them to the swap-cache and to be able to return memory to the
> > > > swap cache as soon as possible on a page-by-page basis.
> > > > Reduce the page max order to the system PMD size, as we can then be nicer
> > > > to the system and avoid splitting gigantic pages.
> > > >
> > > > Looking forward to when we might be able to swap out PMD size folios
> > > > without splitting, this will also be a benefit.
> > > >
> > > > v2:
> > > > - Include all orders up to the PMD size (Christian König)
> > > > v3:
> > > > - Avoid compilation errors for architectures with special PFN_SHIFTs
> > > >
> > > > Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> > > > Reviewed-by: Christian König <christian.koenig at amd.com>
> > > Apparently this fails on ppc build testing. Please supply build fix asap
> > > (or I guess we need to revert). I'm kinda not clear why this only showed
> > > up when I merged the drm-misc-next pr into drm-next ...
> >
> > I'm really wondering this as well. It looks like PMD_SHIFT isn't a constant
> > on this particular platform.
> >
> > But from what I can find in the upstream 6.2 kernel PMD_SHIFT always seems
> > to be a constant.
> >
> > So how exactly can that here break?
>
> There's some in-flight patches to rework MAX_ORDER and other things in
> linux-next, maybe it's recent? If you check out linux-next then you need
> to reapply the patch (since sfr reverted it).
So I looked and on ppc64 PMD_SHIFT is defined in terms of
PTE_INDEX_SIZE, which is defined (for book3s) in terms of the variable
__pte_index_size. This is in 6.3 already and seems pretty old.
So revert? Or fixup patch to make this work on ppc?
> > > > ---
> > > > drivers/gpu/drm/ttm/ttm_pool.c | 30 +++++++++++++++++++-----------
> > > > 1 file changed, 19 insertions(+), 11 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
> > > > index dfce896c4bae..18c342a919a2 100644
> > > > --- a/drivers/gpu/drm/ttm/ttm_pool.c
> > > > +++ b/drivers/gpu/drm/ttm/ttm_pool.c
> > > > @@ -47,6 +47,11 @@
> > > > #include "ttm_module.h"
> > > > +#define TTM_MAX_ORDER (PMD_SHIFT - PAGE_SHIFT)
> > > > +#define __TTM_DIM_ORDER (TTM_MAX_ORDER + 1)
> > > > +/* Some architectures have a weird PMD_SHIFT */
> > > > +#define TTM_DIM_ORDER (__TTM_DIM_ORDER <= MAX_ORDER ? __TTM_DIM_ORDER : MAX_ORDER)
> > > > +
> > > > /**
> > > > * struct ttm_pool_dma - Helper object for coherent DMA mappings
> > > > *
> > > > @@ -65,11 +70,11 @@ module_param(page_pool_size, ulong, 0644);
> > > > static atomic_long_t allocated_pages;
> > > > -static struct ttm_pool_type global_write_combined[MAX_ORDER];
> > > > -static struct ttm_pool_type global_uncached[MAX_ORDER];
> > > > +static struct ttm_pool_type global_write_combined[TTM_DIM_ORDER];
> > > > +static struct ttm_pool_type global_uncached[TTM_DIM_ORDER];
> > > > -static struct ttm_pool_type global_dma32_write_combined[MAX_ORDER];
> > > > -static struct ttm_pool_type global_dma32_uncached[MAX_ORDER];
> > > > +static struct ttm_pool_type global_dma32_write_combined[TTM_DIM_ORDER];
> > > > +static struct ttm_pool_type global_dma32_uncached[TTM_DIM_ORDER];
> > > > static spinlock_t shrinker_lock;
> > > > static struct list_head shrinker_list;
> > > > @@ -444,7 +449,7 @@ int ttm_pool_alloc(struct ttm_pool *pool, struct ttm_tt *tt,
> > > > else
> > > > gfp_flags |= GFP_HIGHUSER;
> > > > - for (order = min_t(unsigned int, MAX_ORDER - 1, __fls(num_pages));
> > > > + for (order = min_t(unsigned int, TTM_MAX_ORDER, __fls(num_pages));
> > > > num_pages;
> > > > order = min_t(unsigned int, order, __fls(num_pages))) {
> > > > struct ttm_pool_type *pt;
> > > > @@ -563,7 +568,7 @@ void ttm_pool_init(struct ttm_pool *pool, struct device *dev,
> > > > if (use_dma_alloc) {
> > > > for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i)
> > > > - for (j = 0; j < MAX_ORDER; ++j)
> > > > + for (j = 0; j < TTM_DIM_ORDER; ++j)
> > > > ttm_pool_type_init(&pool->caching[i].orders[j],
> > > > pool, i, j);
> > > > }
> > > > @@ -583,7 +588,7 @@ void ttm_pool_fini(struct ttm_pool *pool)
> > > > if (pool->use_dma_alloc) {
> > > > for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i)
> > > > - for (j = 0; j < MAX_ORDER; ++j)
> > > > + for (j = 0; j < TTM_DIM_ORDER; ++j)
> > > > ttm_pool_type_fini(&pool->caching[i].orders[j]);
> > > > }
> > > > @@ -637,7 +642,7 @@ static void ttm_pool_debugfs_header(struct seq_file *m)
> > > > unsigned int i;
> > > > seq_puts(m, "\t ");
> > > > - for (i = 0; i < MAX_ORDER; ++i)
> > > > + for (i = 0; i < TTM_DIM_ORDER; ++i)
> > > > seq_printf(m, " ---%2u---", i);
> > > > seq_puts(m, "\n");
> > > > }
> > > > @@ -648,7 +653,7 @@ static void ttm_pool_debugfs_orders(struct ttm_pool_type *pt,
> > > > {
> > > > unsigned int i;
> > > > - for (i = 0; i < MAX_ORDER; ++i)
> > > > + for (i = 0; i < TTM_DIM_ORDER; ++i)
> > > > seq_printf(m, " %8u", ttm_pool_type_count(&pt[i]));
> > > > seq_puts(m, "\n");
> > > > }
> > > > @@ -751,13 +756,16 @@ int ttm_pool_mgr_init(unsigned long num_pages)
> > > > {
> > > > unsigned int i;
> > > > + BUILD_BUG_ON(TTM_DIM_ORDER > MAX_ORDER);
> > > > + BUILD_BUG_ON(TTM_DIM_ORDER < 1);
> > > > +
> > > > if (!page_pool_size)
> > > > page_pool_size = num_pages;
> > > > spin_lock_init(&shrinker_lock);
> > > > INIT_LIST_HEAD(&shrinker_list);
> > > > - for (i = 0; i < MAX_ORDER; ++i) {
> > > > + for (i = 0; i < TTM_DIM_ORDER; ++i) {
> > > > ttm_pool_type_init(&global_write_combined[i], NULL,
> > > > ttm_write_combined, i);
> > > > ttm_pool_type_init(&global_uncached[i], NULL, ttm_uncached, i);
> > > > @@ -790,7 +798,7 @@ void ttm_pool_mgr_fini(void)
> > > > {
> > > > unsigned int i;
> > > > - for (i = 0; i < MAX_ORDER; ++i) {
> > > > + for (i = 0; i < TTM_DIM_ORDER; ++i) {
> > > > ttm_pool_type_fini(&global_write_combined[i]);
> > > > ttm_pool_type_fini(&global_uncached[i]);
> > > > --
> > > > 2.39.2
> > > >
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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