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From:   Tyler Erickson <tyler.erickson@seagate.com>
To:     Rory Chen <rory.c.chen@seagate.com>,
        Paolo Valente <paolo.valente@linaro.org>
CC:     Arie van der Hoeven <arie.vanderhoeven@seagate.com>,
        Muhammad Ahmad <muhammad.ahmad@seagate.com>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jan Kara <jack@suse.cz>,
        "andrea.righi@canonical.com" <andrea.righi@canonical.com>,
        "glen.valante@linaro.org" <glen.valante@linaro.org>,
        "axboe@kernel.dk" <axboe@kernel.dk>,
        Michael English <michael.english@seagate.com>,
        Andrew Ring <andrew.ring@seagate.com>,
        Varun Boddu <varunreddy.boddu@seagate.com>
Subject: RE: [PATCH 0/8] block, bfq: extend bfq to support multi-actuator
 drives
Thread-Topic: [PATCH 0/8] block, bfq: extend bfq to support multi-actuator
 drives
Thread-Index: AQHYhxl16wZu53I2nkyhDu//lRykYq2Hfy1sgB6yWuSAAgaVgIAAJ4jqgAzCDAA=
Date:   Thu, 18 Aug 2022 15:40:59 +0000
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The libata layer is reporting correctly after the changes I submitted.
=20
The drive reports the actuator ranges as a starting LBA and a count of LBAs=
 for the range.
If the code reading the reported values simply does startingLBA + range, th=
is is an incorrect ending LBA for that actuator. This is because LBAs are z=
ero indexed and this simple addition is not taking that into account.
The proper way to get the endingLBA is startingLBA + range - 1 to get the l=
ast LBA value for where to issue a final IO read/write to account for LBA v=
alues starting at zero rather than one.
=20
Here is an example from the output in SeaChest/openSeaChest:
=3D=3D=3D=3DConcurrent Positioning Ranges=3D=3D=3D=3D
=20
Range#     #Elements            Lowest LBA          # of LBAs     =20
   0            1                                               0          =
 17578328064
   1            1                         17578328064           17578328064
=20
If using the incorrect formula to get the final LBA for actuator 0, you wou=
ld get 17578328064, but this is the starting LBA reported by the drive for =
actuator 1.
So to be consistent for all ranges, the final LBA for a given actuator shou=
ld be calculated as starting LBA + range - 1.
=20
I had reached out to Seagate's T10 and T13 representatives for clarificatio=
n and verification and this is most likely what is causing the error is a m=
issing - 1 somewhere after getting the information reported by the device. =
They agreed that the reporting from the drive and the SCSI to ATA translati=
on is correct.
=20
I'm not sure where this is being read and calculated, but it is not an erro=
r in the low-level libata or sd level of the kernel. It may be in bfq, or i=
t may be in some other place after the sd layer. I know there were some add=
itions to read this and report it up the stack, but I did not think those w=
ere wrong as they seemed to pass the drive reported information up the stac=
k.

Tyler Erickson
Seagate Technology


Seagate Internal

-----Original Message-----
From: Rory Chen <rory.c.chen@seagate.com>=20
Sent: Wednesday, August 10, 2022 6:59 AM
To: Paolo Valente <paolo.valente@linaro.org>
Cc: Arie van der Hoeven <arie.vanderhoeven@seagate.com>; Muhammad Ahmad <mu=
hammad.ahmad@seagate.com>; linux-block@vger.kernel.org; linux-kernel@vger.k=
ernel.org; Jan Kara <jack@suse.cz>; andrea.righi@canonical.com; glen.valant=
e@linaro.org; axboe@kernel.dk; Tyler Erickson <tyler.erickson@seagate.com>;=
 Michael English <michael.english@seagate.com>; Andrew Ring <andrew.ring@se=
agate.com>; Varun Boddu <varunreddy.boddu@seagate.com>
Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support multi-actuator d=
rives

The block trace shows the start sector is 35156656120 and transfer length i=
s 8 sectors, which is within the max LBA 35156656127 of drive. And this IO =
is completed successfully from the slice of parsed block trace though repor=
ting the warning message.
 8,64   7       13     0.039401337 19176  Q  RA 35156656120 + 8 [systemd-ud=
evd]
  8,64   7       15     0.039403946 19176  P   N [systemd-udevd]
  8,64   7       16     0.039405132 19176  I  RA 35156656120 + 8 [systemd-u=
devd]
  8,64   7       18     0.039411554 19176  D  RA 35156656120 + 8 [systemd-u=
devd]
  8,64   0       40     0.039479055     0  C  RA 35156656120 + 8 [0]

It may need to know where calculate "bio_end_sector" value as 35156656128. =
I have patched libata and sd driver for Dual Actuator.


From: Paolo Valente <paolo.valente@linaro.org>
Sent: Wednesday, August 10, 2022 6:22 PM
To: Rory Chen <rory.c.chen@seagate.com>
Cc: Arie van der Hoeven <arie.vanderhoeven@seagate.com>; Muhammad Ahmad <mu=
hammad.ahmad@seagate.com>; linux-block@vger.kernel.org <linux-block@vger.ke=
rnel.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>; Jan=
 Kara <jack@suse.cz>; andrea.righi@canonical.com <andrea.righi@canonical.co=
m>; glen.valante@linaro.org <glen.valante@linaro.org>; axboe@kernel.dk <axb=
oe@kernel.dk>; Tyler Erickson <tyler.erickson@seagate.com>; Michael English=
 <michael.english@seagate.com>; Andrew Ring <andrew.ring@seagate.com>; Varu=
n Boddu <varunreddy.boddu@seagate.com>
Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support multi-actuator d=
rives


This message has originated from an External Source. Please use proper judg=
ment and caution when opening attachments, clicking links, or responding to=
 this email.


> Il giorno 9 ago 2022, alle ore 05:47, Rory Chen <rory.c.chen@seagate.com>=
 ha scritto:
>
> Resend the mail as plain text because previous mail with rich text=20
> makes some mess and forget to add others at Seagate who worked on=20
> validating the patch as well(Muhammad, Michael, Andrew, Varun,Tyler)
>
> Hi Paolo,
>

Hi

> I am from Seagate China and face a problem when I'm evaluating the bfq pa=
tches. Could you please check?
> Thanks
>
> Issue statement
> When running performance test on bfq patch, I observed warning message "b=
fq_actuator_index: bio sector out of ranges: end=3D35156656128" and OS hung=
 suddenly after some hours.
> The warning message is reported from function bfq_actuator_index which de=
termines IO request is in which index of actuators.  The bio_end_sector is =
35156656128 but the max LBA for the drive is 35156656127 so it's beyond the=
 LBA range.

Yep, this sanity check fails if the end sector of a new IO does not belong =
to any sector range.

>  I captured the block trace and didn't found request LBA 35156656128 inst=
ead only found max request LBA 35156656127.

Maybe in the trace you see only start sectors?  The failed check si perform=
ed on end sectors instead.

At any rate, there seems to be an off-by-one error in the value(s) stored i=
n the sector field(s) of the blk_independent_access_range data structure.

I guess we may need some help/feedback from people competent on this stuff.

> I'm not sure if this warning message is related to later OS hung.
>

Not easy to say.  At any rate, we can try with a development version of bfq=
.  It can help us detect the possible cause of this hang.  But let's see wh=
ere we get with this sector error first.

Thank you for testing this extended version of bfq, Paolo

>
> Problem environment
> Kernel base is 5.18.9
> Test HDD drive is Seagate ST18000NM0092 dual actuator SATA.
> Actuator LBA mapping by reading VPD B9 Concurrent positioning ranges=20
> VPD page:
> LBA range number:0
> number of storage elements:1
> starting LBA:0x0
> number of LBAs:0x417c00000 [17578328064] LBA range number:1 number of=20
> storage elements:1 starting LBA:0x417c00000 number of LBAs:0x417c00000=20
> [17578328064]
>
>
>
>
>
> From: Paolo Valente <paolo.valente@linaro.org>
> Sent: Thursday, June 23, 2022 8:53 AM
> To: Jens Axboe <axboe@kernel.dk>
> Cc: linux-block@vger.kernel.org <linux-block@vger.kernel.org>;=20
> linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>;=20
> jack@suse.cz <jack@suse.cz>; andrea.righi@canonical.com=20
> <andrea.righi@canonical.com>; glen.valante@linaro.org=20
> <glen.valante@linaro.org>; Arie van der Hoeven=20
> <arie.vanderhoeven@seagate.com>; Paolo Valente=20
> <paolo.valente@linaro.org>
> Subject: [PATCH 0/8] block, bfq: extend bfq to support multi-actuator=20
> drives
>
>
> This message has originated from an External Source. Please use proper ju=
dgment and caution when opening attachments, clicking links, or responding =
to this email.
>
>
> Hi,
> this patch series extends BFQ so as to optimize I/O dispatch to=20
> multi-actuator drives. In particular, this extension addresses the=20
> following issue. Multi-actuator drives appear as a single device to=20
> the I/O subsystem [1].  Yet they address commands to different=20
> actuators internally, as a function of Logical Block Addressing=20
> (LBAs). A given sector is reachable by only one of the actuators. For=20
> example, Seagate's Serial Advanced Technology Attachment (SATA)=20
> version contains two actuators and maps the lower half of the SATA LBA=20
> space to the lower actuator and the upper half to the upper actuator.
>
> Evidently, to fully utilize actuators, no actuator must be left idle=20
> or underutilized while there is pending I/O for it. To reach this=20
> goal, the block layer must somehow control the load of each actuator=20
> individually. This series enriches BFQ with such a per-actuator=20
> control, as a first step. Then it also adds a simple mechanism for=20
> guaranteeing that actuators with pending I/O are never left idle.
>
> See [1] for a more detailed overview of the problem and of the=20
> solutions implemented in this patch series. There you will also find=20
> some preliminary performance results.
>
> Thanks,
> Paolo
>
> [1]=20
> https://secure-web.cisco.com/1hcxnN1C3h1nW7mby7S66_LE8szirQwbQI0fBpYeP
> rA0GTWfyuQyl0GpZaOn32xMSkNT0BUQWloDHFzZ23aYDZdi8NfdrEFLY9pQDBblIvn08LR
> iTVoIOUC8zWSG_r2PCyLtx3ppZq5cWOib_8azxteRRcbKWGdbLPSqg9hfSJSqltth0ByLO
> NHEoI3p3e9QNIn6nVAeQbsT3aOQe-F95XrQvaPrFJXx6RGL9kDXyfkbXIHcdcLBf895gYB
> Fn5S2WjBDQq2kzDzZOlc1HekRUhg0qDQcFY6NydVfrqNfLbpAHAth6KyREscQhVTMVREEV
> a1b6bQByX6grF5pn3pTIo0lODyfX6yRmcbReSYNfOZ65ZPvp-nH530FQ-5nXoRxFf74WIK
> DrNTALs3xQvg03DH4jLez-T2M9xEu-sfEDAEdTGF7BcnmBW6vrPO4_p3k4/https%3A%2F
> %2Fwww.linaro.org%2Fblog%2Fbudget-fair-queueing-bfq-linux-io-scheduler
> -optimizations-for-multi-actuator-sata-hard-drives%2F
>
> Davide Zini (3):
>  block, bfq: split also async bfq_queues on a per-actuator basis =20
> block, bfq: inject I/O to underutilized actuators  block, bfq: balance=20
> I/O injection among underutilized actuators
>
> Federico Gavioli (1):
>  block, bfq: retrieve independent access ranges from request queue
>
> Paolo Valente (4):
>  block, bfq: split sync bfq_queues on a per-actuator basis  block,=20
> bfq: forbid stable merging of queues associated with different
>    actuators
>  block, bfq: turn scalar fields into arrays in bfq_io_cq  block, bfq:=20
> turn BFQ_NUM_ACTUATORS into BFQ_MAX_ACTUATORS
>
> block/bfq-cgroup.c  |  97 +++++----
> block/bfq-iosched.c | 488 +++++++++++++++++++++++++++++---------------
> block/bfq-iosched.h | 149 ++++++++++----
> block/bfq-wf2q.c    |   2 +-
> 4 files changed, 493 insertions(+), 243 deletions(-)
>
> --
> 2.20.1
>
>
> Seagate Internal
>
> Seagate Internal

Seagate Internal