Re: [PATCH 07/12] scsi_debug: use likely hints on fast path

[Bart Van Assche]

On 04/25/2016 09:16 AM, Douglas Gilbert wrote:
-       if ((SDEBUG_OPT_MEDIUM_ERR & sdebug_opts) &&
-           (lba <= (OPT_MEDIUM_ERR_ADDR + OPT_MEDIUM_ERR_NUM - 1)) &&
-           ((lba + num) > OPT_MEDIUM_ERR_ADDR)) {
+       if (unlikely((SDEBUG_OPT_MEDIUM_ERR & sdebug_opts) &&
+                    (lba <= (OPT_MEDIUM_ERR_ADDR + OPT_MEDIUM_ERR_NUM - 1)) &&
+                    ((lba + num) > OPT_MEDIUM_ERR_ADDR))) {
> [ ... ]
-       if ((qa_indx < 0) || (qa_indx >= SCSI_DEBUG_CANQUEUE)) {
+       if (unlikely((qa_indx < 0) || (qa_indx >= SCSI_DEBUG_CANQUEUE))) {
> [ ... ]
-       if ((qdepth > 0) && (num_in_q >= qdepth)) {
+       if (unlikely((qdepth > 0) && (num_in_q >= qdepth))) {
> [ ... ]
-       } else if ((sdebug_every_nth != 0) &&
-                  (SDEBUG_OPT_RARE_TSF & sdebug_opts) &&
-                  (scsi_result == 0)) {
+       } else if (unlikely((sdebug_every_nth != 0) &&
+                           (SDEBUG_OPT_RARE_TSF & sdebug_opts) &&
+                           (scsi_result == 0))) {

Since you are modifying this code, please remove the superfluous 
parentheses.

> -  struct sdebug_host_info * sdbg_host;
> -  struct sdebug_dev_info * open_devip = NULL;
> -  struct sdebug_dev_info * devip =
> -                  (struct sdebug_dev_info *)sdev->hostdata;
> +  struct sdebug_host_info *sdbg_host;
> +  struct sdebug_dev_info *open_devip = NULL;
> +  struct sdebug_dev_info *devip;
>
> -  if (devip)
> -          return devip;

Has this change been described in the patch description?

@@ -4632,9 +4617,11 @@ static int __init scsi_debug_init(void)
        switch (sdebug_dif) {

        case SD_DIF_TYPE0_PROTECTION:
+               break;
        case SD_DIF_TYPE1_PROTECTION:
        case SD_DIF_TYPE2_PROTECTION:
        case SD_DIF_TYPE3_PROTECTION:
+               have_dif_prot = true;
                break;

Same comment for this code: has this change been explained in the patch 
description?

Bart.
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