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SubjectRe: [PATCH v29 4/4] scsi: ufs: Add HPB 2.0 support
On 2021-03-15 09:31, Daejun Park wrote:
> This patch supports the HPB 2.0.
>
> The HPB 2.0 supports read of varying sizes from 4KB to 512KB.
> In the case of Read (<= 32KB) is supported as single HPB read.
> In the case of Read (36KB ~ 512KB) is supported by as a combination of
> write buffer command and HPB read command to deliver more PPN.
> The write buffer commands may not be issued immediately due to busy
> tags.
> To use HPB read more aggressively, the driver can requeue the write
> buffer
> command. The requeue threshold is implemented as timeout and can be
> modified with requeue_timeout_ms entry in sysfs.
>
> Signed-off-by: Daejun Park <daejun7.park@samsung.com>
> ---
> +static struct attribute *hpb_dev_param_attrs[] = {
> + &dev_attr_requeue_timeout_ms.attr,
> + NULL,
> +};
> +
> +struct attribute_group ufs_sysfs_hpb_param_group = {
> + .name = "hpb_param_sysfs",
> + .attrs = hpb_dev_param_attrs,
> +};
> +
> +static int ufshpb_pre_req_mempool_init(struct ufshpb_lu *hpb)
> +{
> + struct ufshpb_req *pre_req = NULL;
> + int qd = hpb->sdev_ufs_lu->queue_depth / 2;
> + int i, j;
> +
> + INIT_LIST_HEAD(&hpb->lh_pre_req_free);
> +
> + hpb->pre_req = kcalloc(qd, sizeof(struct ufshpb_req), GFP_KERNEL);
> + hpb->throttle_pre_req = qd;
> + hpb->num_inflight_pre_req = 0;
> +
> + if (!hpb->pre_req)
> + goto release_mem;
> +
> + for (i = 0; i < qd; i++) {
> + pre_req = hpb->pre_req + i;
> + INIT_LIST_HEAD(&pre_req->list_req);
> + pre_req->req = NULL;
> + pre_req->bio = NULL;

Why don't prepare bio as same as wb.m_page? Won't that save more time
for ufshpb_issue_pre_req()?

Thanks,
Can Guo.

> +
> + pre_req->wb.m_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
> + if (!pre_req->wb.m_page) {
> + for (j = 0; j < i; j++)
> + __free_page(hpb->pre_req[j].wb.m_page);
> +
> + goto release_mem;
> + }
> + list_add_tail(&pre_req->list_req, &hpb->lh_pre_req_free);
> + }
> +
> + return 0;
> +release_mem:
> + kfree(hpb->pre_req);
> + return -ENOMEM;
> +}
> +

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