Currently, we are thinking about the solution to the problem. However, because
the end time of v5.11 is approaching, this patch is sent first.
On 2021/1/29 17:21, Zhen Lei wrote:
> This reverts commit 4e89dce725213d3d0b0475211b500eda4ef4bf2f.
>
> We find that this patch has a great impact on performance. According to
> our test: the iops decreases from 1655.6K to 893.5K, about half.
>
> Hardware: 1 SAS expander with 12 SAS SSD
> Command: Only the main parameters are listed.
> fio bs=4k rw=read iodepth=128 cpus_allowed=0-127
>
> Fixes: 4e89dce72521 ("iommu/iova: Retry from last rb tree node if iova search
> fails")
> Tested-by: Xiang Chen <[email protected]>
> Signed-off-by: Zhen Lei <[email protected]>
> ---
> drivers/iommu/iova.c | 23 ++++++-----------------
> 1 file changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index d20b8b333d30d17..f840c7207efbced 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -185,9 +185,8 @@ static int __alloc_and_insert_iova_range(struct
> iova_domain *iovad,
> struct rb_node *curr, *prev;
> struct iova *curr_iova;
> unsigned long flags;
> - unsigned long new_pfn, retry_pfn;
> + unsigned long new_pfn;
> unsigned long align_mask = ~0UL;
> - unsigned long high_pfn = limit_pfn, low_pfn = iovad->start_pfn;
>
> if (size_aligned)
> align_mask <<= fls_long(size - 1);
> @@ -200,25 +199,15 @@ static int __alloc_and_insert_iova_range(struct
> iova_domain *iovad,
>
> curr = __get_cached_rbnode(iovad, limit_pfn);
> curr_iova = rb_entry(curr, struct iova, node);
> - retry_pfn = curr_iova->pfn_hi + 1;
> -
> -retry:
> do {
> - high_pfn = min(high_pfn, curr_iova->pfn_lo);
> - new_pfn = (high_pfn - size) & align_mask;
> + limit_pfn = min(limit_pfn, curr_iova->pfn_lo);
> + new_pfn = (limit_pfn - size) & align_mask;
> prev = curr;
> curr = rb_prev(curr);
> curr_iova = rb_entry(curr, struct iova, node);
> - } while (curr && new_pfn <= curr_iova->pfn_hi && new_pfn >= low_pfn);
> -
> - if (high_pfn < size || new_pfn < low_pfn) {
> - if (low_pfn == iovad->start_pfn && retry_pfn < limit_pfn) {
> - high_pfn = limit_pfn;
> - low_pfn = retry_pfn;
> - curr = &iovad->anchor.node;
> - curr_iova = rb_entry(curr, struct iova, node);
> - goto retry;
> - }
> + } while (curr && new_pfn <= curr_iova->pfn_hi);
> +
> + if (limit_pfn < size || new_pfn < iovad->start_pfn) {
> iovad->max32_alloc_size = size;
> goto iova32_full;
> }
>
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