Re: [PATCH v5 0/6] mm/vmalloc: Speed up ioremap, vmalloc and vmap with contiguous memory

On Mon, Jul 6, 2026 at 4:43 PM Wen Jiang [off-list ref] wrote:

This patchset accelerates ioremap, vmalloc, and vmap when the memory
is physically fully or partially contiguous. Two techniques are used:

1. Avoid page table rewalk when setting PTEs/PMDs for multiple memory
   segments
2. Use batched mappings wherever possible in both vmalloc and ARM64
   layers

Besides accelerating the mapping path, this also enables large
mappings (PMD and cont-PTE) for vmap, which are currently not
supported.

Patches 1-2 extend ARM64 vmalloc CONT-PTE mapping to support multiple
CONT-PTE regions instead of just one.

Patch 3 extracts a common helper vmap_set_ptes() that consolidates PTE
mapping logic between the ioremap and vmalloc/vmap paths, handling both
CONT_PTE and regular PTE mappings. This prepares for the next patch.

Patch 4 extends the page table walk path to support page shifts other
than PAGE_SHIFT and eliminates the page table rewalk for huge vmalloc
mappings. The function is renamed from vmap_small_pages_range_noflush()
to vmap_pages_range_noflush_walk().

Patches 5-6 add huge vmap support for contiguous pages, including
support for non-compound pages with pfn alignment verification.

On the RK3588 8-core ARM64 SoC, with tasks pinned to a little core and
the performance CPUfreq policy enabled, benchmark results:

* ioremap(1 MB): 1.35x faster (3407 ns -> 2526 ns)
* vmalloc(1 MB) mapping time (excluding allocation) with
  VM_ALLOW_HUGE_VMAP: 1.42x faster (5.00 us -> 3.53us)
* vmap(100MB) with order-8 pages: 8.3x faster (1235 us -> 149 us)

Many thanks to Xueyuan Chen for his testing efforts on RK3588 boards.

Please also put Leo's data here[1] and also please collect Leo's tags in all
patches.

Tested-by: Leo Yan <leo.yan@arm.com>

[1] https://lore.kernel.org/linux-mm/20260626151214.GA1794676@e132581.arm.com/ (local)