Re: [PATCH v2] mm: shmem: skip swapcache for swapin of synchronous swap device

[Matthew Wilcox]

On Thu, Jan 02, 2025 at 04:40:17PM +0800, Baolin Wang wrote:
> With fast swap devices (such as zram), swapin latency is crucial to applications.
> For shmem swapin, similar to anonymous memory swapin, we can skip the swapcache
> operation to improve swapin latency.

OK, but now we have more complexity.  Why can't we always skip the
swapcache on swapin?  (Actually, I think we can always skip the
swapcache on swapout too, but that's a different matter).

> +static struct folio *shmem_swap_alloc_folio(struct inode *inode, struct vm_area_struct *vma,
> +					    pgoff_t index, swp_entry_t entry, int order, gfp_t gfp)

Please wrap at 80 columns and use two tabs for indenting subsequent
lines.  ie:

static struct folio *shmem_swap_alloc_folio(struct inode *inode,
		struct vm_area_struct *vma, pgoff_t index, swp_entry_t entry,
		int order, gfp_t gfp)