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From: Sumit Saxena <sumit.saxena@avagotech.com>
To: Tomas Henzl <thenzl@redhat.com>,
	jbottomley@parallels.com, hch@infradead.org,
	martin.petersen@oracle.com
Cc: linux-scsi@vger.kernel.org, Kashyap Desai <kashyap.desai@avagotech.com>
Subject: RE: [PATCH 10/15] megaraid_sas: IO throttling support
Date: Thu, 28 Jan 2016 12:48:13 +0530	[thread overview]
Message-ID: <75f584b953b9ad3a901011e049e3715e@mail.gmail.com> (raw)
In-Reply-To: <569E3C3C.6040507@redhat.com>

> -----Original Message-----
> From: Tomas Henzl [mailto:thenzl@redhat.com]
> Sent: Tuesday, January 19, 2016 7:08 PM
> To: Sumit Saxena; jbottomley@parallels.com; hch@infradead.org;
> martin.petersen@oracle.com
> Cc: linux-scsi@vger.kernel.org; kashyap.desai@avagotech.com
> 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@avagotech.com>
> > Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
> > ---
> >  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;

  reply	other threads:[~2016-01-28  7:18 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-18 13:26 [PATCH 00/15] megaraid_sas: Updates for scsi-next Sumit Saxena
2015-12-18 13:26 ` [PATCH 01/15] megaraid_sas: Do not allow PCI access during OCR Sumit Saxena
2016-01-11 17:02   ` Tomas Henzl
2015-12-18 13:26 ` [PATCH 02/15] megaraid_sas: MFI IO timeout handling Sumit Saxena
2016-01-11 17:02   ` Tomas Henzl
2015-12-18 13:26 ` [PATCH 03/15] megaraid_sas: Syncing request flags macro names with firmware Sumit Saxena
2016-01-11 17:03   ` Tomas Henzl
2015-12-18 13:26 ` [PATCH 04/15] megaraid_sas: Task management support Sumit Saxena
2016-01-11 17:03   ` Tomas Henzl
2016-01-14 12:04     ` Sumit Saxena
2015-12-18 13:26 ` [PATCH 05/15] megaraid_sas: Update device Queue depth based on interface type Sumit Saxena
2016-01-12 14:16   ` Tomas Henzl
2016-01-14 11:48     ` Sumit Saxena
2015-12-18 13:26 ` [PATCH 06/15] megaraid_sas: Fastpath region lock bypass Sumit Saxena
2016-01-12 14:44   ` Tomas Henzl
2015-12-18 13:27 ` [PATCH 07/15] megaraid_sas: Reply Descriptor Post Queue(RDPQ) support Sumit Saxena
2015-12-18 14:49   ` [PATCH] megaraid_sas: fix kzalloc-simple.cocci warnings kbuild test robot
2015-12-18 14:49   ` [PATCH 07/15] megaraid_sas: Reply Descriptor Post Queue(RDPQ) support kbuild test robot
2016-01-14 17:38   ` Tomas Henzl
2016-01-27 18:15     ` Sumit Saxena
2015-12-18 13:27 ` [PATCH 08/15] megaraid_sas: Code optimization build_and_issue_cmd return-type Sumit Saxena
2016-01-14 18:05   ` Tomas Henzl
2015-12-18 13:27 ` [PATCH 09/15] megaraid_sas: Dual Queue depth support Sumit Saxena
2016-01-19 13:34   ` Tomas Henzl
2016-01-19 13:44     ` Sumit Saxena
2016-01-20 13:55       ` Tomas Henzl
2016-01-20 14:09         ` Sumit Saxena
2016-01-20 14:16           ` Tomas Henzl
2016-01-20 15:08             ` Sumit Saxena
2016-01-20 16:00               ` Tomas Henzl
2016-01-27  2:02             ` Martin K. Petersen
2016-01-27  7:09               ` Sumit Saxena
2015-12-18 13:27 ` [PATCH 10/15] megaraid_sas: IO throttling support Sumit Saxena
2016-01-19 13:38   ` Tomas Henzl
2016-01-28  7:18     ` Sumit Saxena [this message]
2015-12-18 13:27 ` [PATCH 11/15] megaraid_sas: Make adprecovery variable atomic Sumit Saxena
2016-01-19 13:52   ` Tomas Henzl
2016-01-28  8:30     ` Sumit Saxena
2015-12-18 13:27 ` [PATCH 12/15] megaraid_sas: MFI adapter's OCR changes Sumit Saxena
2016-01-19 14:22   ` Tomas Henzl
2016-01-28 11:12     ` Sumit Saxena
2015-12-18 13:27 ` [PATCH 13/15] megaraid_sas: Introduce module parameter for SCSI command-timeout Sumit Saxena
2016-01-19 14:57   ` Tomas Henzl
2016-01-28 11:17     ` Sumit Saxena
2015-12-18 13:27 ` [PATCH 14/15] megaraid_sas: SPERC OCR changes Sumit Saxena
2016-01-19 15:14   ` Tomas Henzl
2015-12-18 13:27 ` [PATCH 15/15] megaraid_sas: SPERC boot driver reorder Sumit Saxena
2015-12-18 14:05   ` Christoph Hellwig
2016-01-08  7:07     ` Sumit Saxena
2016-01-12  5:26     ` Sumit Saxena

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