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[SCSI] lpfc: Adjust lpfc_scsi_buf allocation

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Adjust lpfc_scsi_buf allocation to account for lun_queue_depth and
error handling

Under high load and high duress, the error handler could steal some
command resources from the normal i/o path. Rework to allocate
additional resources to avoid this scneario.

Signed-off-by: James Smart <James.Smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
James.Smart@Emulex.Com 2005-10-28 20:29:51 -04:00 committed by James Bottomley
parent 68876920f4
commit a784efbff7
1 changed files with 16 additions and 7 deletions
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23
drivers/scsi/lpfc/lpfc_scsi.c
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@ -1152,24 +1152,33 @@ lpfc_slave_alloc(struct scsi_device *sdev)
/*
* Populate the cmds_per_lun count scsi_bufs into this host's globally
* available list of scsi buffers. Don't allocate more than the
* HBA limit conveyed to the midlayer via the host structure. Note
* that this list of scsi bufs exists for the lifetime of the driver.
* HBA limit conveyed to the midlayer via the host structure. The
* formula accounts for the lun_queue_depth + error handlers + 1
* extra. This list of scsi bufs exists for the lifetime of the driver.
*/
total = phba->total_scsi_bufs;
num_to_alloc = LPFC_CMD_PER_LUN;
num_to_alloc = phba->cfg_lun_queue_depth + 2;
if (total >= phba->cfg_hba_queue_depth) {
printk(KERN_WARNING "%s, At config limitation of "
"%d allocated scsi_bufs\n", __FUNCTION__, total);
lpfc_printf_log(phba, KERN_WARNING, LOG_FCP,
"%d:0704 At limitation of %d preallocated "
"command buffers\n", phba->brd_no, total);
return 0;
} else if (total + num_to_alloc > phba->cfg_hba_queue_depth) {
lpfc_printf_log(phba, KERN_WARNING, LOG_FCP,
"%d:0705 Allocation request of %d command "
"buffers will exceed max of %d. Reducing "
"allocation request to %d.\n", phba->brd_no,
num_to_alloc, phba->cfg_hba_queue_depth,
(phba->cfg_hba_queue_depth - total));
num_to_alloc = phba->cfg_hba_queue_depth - total;
}
for (i = 0; i < num_to_alloc; i++) {
scsi_buf = lpfc_get_scsi_buf(phba);
if (!scsi_buf) {
printk(KERN_ERR "%s, failed to allocate "
"scsi_buf\n", __FUNCTION__);
lpfc_printf_log(phba, KERN_ERR, LOG_FCP,
"%d:0706 Failed to allocate command "
"buffer\n", phba->brd_no);
break;
}