> -----Original Message----- > From: Tomas Henzl [mailto:thenzl@xxxxxxxxxx] > Sent: Tuesday, January 19, 2016 7:08 PM > To: Sumit Saxena; jbottomley@xxxxxxxxxxxxx; hch@xxxxxxxxxxxxx; > martin.petersen@xxxxxxxxxx > Cc: linux-scsi@xxxxxxxxxxxxxxx; kashyap.desai@xxxxxxxxxxxxx > Subject: Re: [PATCH 10/15] megaraid_sas: IO throttling support > > On 18.12.2015 14:27, Sumit Saxena wrote: > > This patch will add capability in driver to tell firmware that it can > > throttle IOs in case Controller's Queue depth is downgraded post OFU (Online > firmware upgrade). This feature will ensure firmware can be downgraded from > higher queue depth to lower queue depth without needing system reboot. > > Added throttling code in IO path of driver, in case OS tries to send more IOs > than post OFU firmware's queue depth. > > > > Signed-off-by: Sumit Saxena <sumit.saxena@xxxxxxxxxxxxx> > > Signed-off-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxxx> > > --- > > drivers/scsi/megaraid/megaraid_sas.h | 6 ++++-- > > drivers/scsi/megaraid/megaraid_sas_fusion.c | 7 +++++++ > > 2 files changed, 11 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/scsi/megaraid/megaraid_sas.h > > b/drivers/scsi/megaraid/megaraid_sas.h > > index 4595ef4..9d2b3da 100644 > > --- a/drivers/scsi/megaraid/megaraid_sas.h > > +++ b/drivers/scsi/megaraid/megaraid_sas.h > > @@ -1537,7 +1537,8 @@ union megasas_sgl_frame { typedef union > > _MFI_CAPABILITIES { > > struct { > > #if defined(__BIG_ENDIAN_BITFIELD) > > - u32 reserved:21; > > + u32 reserved:20; > > + u32 support_qd_throttling:1; > > u32 support_fp_rlbypass:1; > > u32 support_vfid_in_ioframe:1; > > u32 support_ext_io_size:1; > > @@ -1561,7 +1562,8 @@ typedef union _MFI_CAPABILITIES { > > u32 support_ext_io_size:1; > > u32 support_vfid_in_ioframe:1; > > u32 support_fp_rlbypass:1; > > - u32 reserved:21; > > + u32 support_qd_throttling:1; > > + u32 reserved:20; > > #endif > > } mfi_capabilities; > > __le32 reg; > > diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c > > b/drivers/scsi/megaraid/megaraid_sas_fusion.c > > index 7cc7806..1248c7a 100644 > > --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c > > +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c > > @@ -801,6 +801,7 @@ megasas_ioc_init_fusion(struct megasas_instance > *instance) > > if (!dual_qdepth_disable) > > drv_ops->mfi_capabilities.support_ext_queue_depth = 1; > > > > + drv_ops->mfi_capabilities.support_qd_throttling = 1; > > /* Convert capability to LE32 */ > > cpu_to_le32s((u32 > > *)&init_frame->driver_operations.mfi_capabilities); > > > > @@ -2182,6 +2183,12 @@ megasas_build_and_issue_cmd_fusion(struct > megasas_instance *instance, > > atomic_inc(&instance->ldio_outstanding); > > } > > > > + if (atomic_read(&instance->fw_outstanding) >= > > + instance->host->can_queue) { > > + dev_err(&instance->pdev->dev, "Throttle IOs beyond Controller > queue depth\n"); > > + return SCSI_MLQUEUE_HOST_BUSY; > > + } > > Same as in the previous patch, this this test above won't you protect when > several processes read the same value in parallel. In addition to that, when the > scsi layer knows the new smaller can_queue value it will not queue new > commands above the limit. Agree that SCSI mid layer itself will not send IOs beyond can_queue value and we can remove this code. This code was just extra check for older kernels- if IOs returned to SCSI mid layer by driver with DID_RESET status does not check updated can_queue value(not sure if it was always taken care of so added this code). > > > + > > cmd = megasas_get_cmd_fusion(instance, scmd->request->tag); > > > > index = cmd->index; -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
