On Thu, Nov 28, 2024 at 03:40:41PM +0800, Baolin Wang wrote: > Add large folio support for tmpfs write and fallocate paths matching the > same high order preference mechanism used in the iomap buffered IO path > as used in __filemap_get_folio(). > > Add shmem_mapping_size_orders() to get a hint for the orders of the folio > based on the file size which takes care of the mapping requirements. > > Traditionally, tmpfs only supported PMD-sized large folios. However nowadays > with other file systems supporting any sized large folios, and extending > anonymous to support mTHP, we should not restrict tmpfs to allocating only > PMD-sized large folios, making it more special. Instead, we should allow > tmpfs can allocate any sized large folios. > > Considering that tmpfs already has the 'huge=' option to control the PMD-sized > large folios allocation, we can extend the 'huge=' option to allow any sized > large folios. The semantics of the 'huge=' mount option are: > > huge=never: no any sized large folios > huge=always: any sized large folios > huge=within_size: like 'always' but respect the i_size > huge=advise: like 'always' if requested with madvise() > > Note: for tmpfs mmap() faults, due to the lack of a write size hint, still > allocate the PMD-sized huge folios if huge=always/within_size/advise is set. > > Moreover, the 'deny' and 'force' testing options controlled by > '/sys/kernel/mm/transparent_hugepage/shmem_enabled', still retain the same > semantics. The 'deny' can disable any sized large folios for tmpfs, while > the 'force' can enable PMD sized large folios for tmpfs. > > Co-developed-by: Daniel Gomez <da.go...@samsung.com> > Signed-off-by: Daniel Gomez <da.go...@samsung.com> > Signed-off-by: Baolin Wang <baolin.w...@linux.alibaba.com>
Hi, This causes a huge regression in Intel iGPU texturing performance. I haven't had time to look at this in detail, but presumably the problem is that we're no longer getting huge pages from our private tmpfs mount (done in i915_gemfs_init()). Some more details at https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13845 > --- > mm/shmem.c | 99 ++++++++++++++++++++++++++++++++++++++++++++---------- > 1 file changed, 81 insertions(+), 18 deletions(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 7595c3db4c1c..54eaa724c153 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -554,34 +554,100 @@ static bool shmem_confirm_swap(struct address_space > *mapping, > > static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER; > > +/** > + * shmem_mapping_size_orders - Get allowable folio orders for the given file > size. > + * @mapping: Target address_space. > + * @index: The page index. > + * @write_end: end of a write, could extend inode size. > + * > + * This returns huge orders for folios (when supported) based on the file > size > + * which the mapping currently allows at the given index. The index is > relevant > + * due to alignment considerations the mapping might have. The returned order > + * may be less than the size passed. > + * > + * Return: The orders. > + */ > +static inline unsigned int > +shmem_mapping_size_orders(struct address_space *mapping, pgoff_t index, > loff_t write_end) > +{ > + unsigned int order; > + size_t size; > + > + if (!mapping_large_folio_support(mapping) || !write_end) > + return 0; > + > + /* Calculate the write size based on the write_end */ > + size = write_end - (index << PAGE_SHIFT); > + order = filemap_get_order(size); > + if (!order) > + return 0; > + > + /* If we're not aligned, allocate a smaller folio */ > + if (index & ((1UL << order) - 1)) > + order = __ffs(index); > + > + order = min_t(size_t, order, MAX_PAGECACHE_ORDER); > + return order > 0 ? BIT(order + 1) - 1 : 0; > +} > + > static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t > index, > loff_t write_end, bool > shmem_huge_force, > + struct vm_area_struct *vma, > unsigned long vm_flags) > { > + unsigned int maybe_pmd_order = HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER ? > + 0 : BIT(HPAGE_PMD_ORDER); > + unsigned long within_size_orders; > + unsigned int order; > + pgoff_t aligned_index; > loff_t i_size; > > - if (HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER) > - return 0; > if (!S_ISREG(inode->i_mode)) > return 0; > if (shmem_huge == SHMEM_HUGE_DENY) > return 0; > if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE) > - return BIT(HPAGE_PMD_ORDER); > + return maybe_pmd_order; > > + /* > + * The huge order allocation for anon shmem is controlled through > + * the mTHP interface, so we still use PMD-sized huge order to > + * check whether global control is enabled. > + * > + * For tmpfs mmap()'s huge order, we still use PMD-sized order to > + * allocate huge pages due to lack of a write size hint. > + * > + * Otherwise, tmpfs will allow getting a highest order hint based on > + * the size of write and fallocate paths, then will try each allowable > + * huge orders. > + */ > switch (SHMEM_SB(inode->i_sb)->huge) { > case SHMEM_HUGE_ALWAYS: > - return BIT(HPAGE_PMD_ORDER); > + if (vma) > + return maybe_pmd_order; > + > + return shmem_mapping_size_orders(inode->i_mapping, index, > write_end); > case SHMEM_HUGE_WITHIN_SIZE: > - index = round_up(index + 1, HPAGE_PMD_NR); > - i_size = max(write_end, i_size_read(inode)); > - i_size = round_up(i_size, PAGE_SIZE); > - if (i_size >> PAGE_SHIFT >= index) > - return BIT(HPAGE_PMD_ORDER); > + if (vma) > + within_size_orders = maybe_pmd_order; > + else > + within_size_orders = > shmem_mapping_size_orders(inode->i_mapping, > + index, > write_end); > + > + order = highest_order(within_size_orders); > + while (within_size_orders) { > + aligned_index = round_up(index + 1, 1 << order); > + i_size = max(write_end, i_size_read(inode)); > + i_size = round_up(i_size, PAGE_SIZE); > + if (i_size >> PAGE_SHIFT >= aligned_index) > + return within_size_orders; > + > + order = next_order(&within_size_orders, order); > + } > fallthrough; > case SHMEM_HUGE_ADVISE: > if (vm_flags & VM_HUGEPAGE) > - return BIT(HPAGE_PMD_ORDER); > + return maybe_pmd_order; > fallthrough; > default: > return 0; > @@ -781,6 +847,7 @@ static unsigned long shmem_unused_huge_shrink(struct > shmem_sb_info *sbinfo, > > static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t > index, > loff_t write_end, bool > shmem_huge_force, > + struct vm_area_struct *vma, > unsigned long vm_flags) > { > return 0; > @@ -1176,7 +1243,7 @@ static int shmem_getattr(struct mnt_idmap *idmap, > STATX_ATTR_NODUMP); > generic_fillattr(idmap, request_mask, inode, stat); > > - if (shmem_huge_global_enabled(inode, 0, 0, false, 0)) > + if (shmem_huge_global_enabled(inode, 0, 0, false, NULL, 0)) > stat->blksize = HPAGE_PMD_SIZE; > > if (request_mask & STATX_BTIME) { > @@ -1693,14 +1760,10 @@ unsigned long shmem_allowable_huge_orders(struct > inode *inode, > return 0; > > global_orders = shmem_huge_global_enabled(inode, index, write_end, > - shmem_huge_force, vm_flags); > - if (!vma || !vma_is_anon_shmem(vma)) { > - /* > - * For tmpfs, we now only support PMD sized THP if huge page > - * is enabled, otherwise fallback to order 0. > - */ > + shmem_huge_force, vma, > vm_flags); > + /* Tmpfs huge pages allocation */ > + if (!vma || !vma_is_anon_shmem(vma)) > return global_orders; > - } > > /* > * Following the 'deny' semantics of the top level, force the huge > -- > 2.39.3 > -- Ville Syrjälä Intel
