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Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support multi-actuator
 drives
From:   Paolo Valente <paolo.valente@linaro.org>
In-Reply-To: <SJ0PR20MB44099E58A9EF256E849C8FF4A0549@SJ0PR20MB4409.namprd20.prod.outlook.com>
Date:   Fri, 30 Sep 2022 17:48:40 +0200
Cc:     Arie van der Hoeven <arie.vanderhoeven@seagate.com>,
        Tyler Erickson <tyler.erickson@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>,
        Damien Le Moal <damien.lemoal@wdc.com>
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Message-Id: <09055269-6707-402C-9A69-2BA720886E17@linaro.org>
References: <20220623155335.6147-1-paolo.valente@linaro.org>
 <PH7PR20MB505849512979A89E8A66FB24F18E9@PH7PR20MB5058.namprd20.prod.outlook.com>
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 <SJ0PR20MB44099E58A9EF256E849C8FF4A0549@SJ0PR20MB4409.namprd20.prod.outlook.com>
To:     Rory Chen <rory.c.chen@seagate.com>
Precedence: bulk


> Il giorno 28 set 2022, alle ore 03:02, Rory Chen =
<rory.c.chen@seagate.com> ha scritto:
>=20
> Hi Arie,
>=20
> I have no experience to submit the change into kernel. Can Paolo or =
other maintainers help submit?
>=20
>=20

Hi Rory,
the problem here is that your change simply switches off the warning
in BFQ, but the offending sector number is still produced by
bio_end_sector.  What we need here is some feedback by Damien or Jens.
Maybe they are not following this thread.  I'll try to get their
attention by creating a new thread on the topic.  Cross your fingers :)

Thanks,
Paolo

> Seagate Internal
>=20
> -----Original Message-----
> From: Arie van der Hoeven <arie.vanderhoeven@seagate.com>=20
> Sent: Wednesday, September 28, 2022 12:59 AM
> To: Rory Chen <rory.c.chen@seagate.com>; Paolo Valente =
<paolo.valente@linaro.org>
> Cc: Tyler Erickson <tyler.erickson@seagate.com>; Muhammad Ahmad =
<muhammad.ahmad@seagate.com>; linux-block@vger.kernel.org; =
linux-kernel@vger.kernel.org; Jan Kara <jack@suse.cz>; =
andrea.righi@canonical.com; glen.valante@linaro.org; axboe@kernel.dk; =
Michael English <michael.english@seagate.com>; Andrew Ring =
<andrew.ring@seagate.com>; Varun Boddu <varunreddy.boddu@seagate.com>; =
Damien Le Moal <damien.lemoal@wdc.com>
> Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support =
multi-actuator drives
>=20
> Chiming in as we have customers who are having very good results with =
these BFQ patches and are planning to pilot NAS solutions in early 2023. =
This bug is not a blocker for us, but we do need the BFQ patches =
included in Linux 6.0.
>=20
> Rory can you submit your changes or is it the maintainer's =
responsibility?
>=20
> Regards,  --Arie
>=20
>=20
> From: Rory Chen <mailto:rory.c.chen@seagate.com>
> Sent: Thursday, September 8, 2022 4:34 AM
> To: Paolo Valente <mailto:paolo.valente@linaro.org>
> Cc: Tyler Erickson <mailto:tyler.erickson@seagate.com>; Arie van der =
Hoeven <mailto:arie.vanderhoeven@seagate.com>; Muhammad Ahmad =
<mailto:muhammad.ahmad@seagate.com>; mailto:linux-block@vger.kernel.org =
<mailto:linux-block@vger.kernel.org>; =
mailto:linux-kernel@vger.kernel.org =
<mailto:linux-kernel@vger.kernel.org>; Jan Kara <mailto:jack@suse.cz>; =
mailto:andrea.righi@canonical.com <mailto:andrea.righi@canonical.com>; =
mailto:glen.valante@linaro.org <mailto:glen.valante@linaro.org>; =
mailto:axboe@kernel.dk <mailto:axboe@kernel.dk>; Michael English =
<mailto:michael.english@seagate.com>; Andrew Ring =
<mailto:andrew.ring@seagate.com>; Varun Boddu =
<mailto:varunreddy.boddu@seagate.com>; Damien Le Moal =
<mailto:damien.lemoal@wdc.com>
> Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support =
multi-actuator drives
>=20
>=20
> Oops, I attach wrong code change. Here's the right change made by me.
>=20
> <               if (end >=3D iar->sector + 1 && end < iar->sector + =
iar->nr_sectors + 1)  //Changed code
>>              if (end >=3D iar->sector && end < iar->sector +=20
>> iar->nr_sectors) // Original code
>=20
> Unfortunately, the crash is still existing and I can't find any clue =
from /var/log/messages
>=20
>=20
>=20
> From: Paolo Valente <mailto:paolo.valente@linaro.org>
> Sent: Thursday, September 8, 2022 6:54 PM
> To: Rory Chen <mailto:rory.c.chen@seagate.com>
> Cc: Tyler Erickson <mailto:tyler.erickson@seagate.com>; Arie van der =
Hoeven <mailto:arie.vanderhoeven@seagate.com>; Muhammad Ahmad =
<mailto:muhammad.ahmad@seagate.com>; mailto:linux-block@vger.kernel.org =
<mailto:linux-block@vger.kernel.org>; =
mailto:linux-kernel@vger.kernel.org =
<mailto:linux-kernel@vger.kernel.org>; Jan Kara <mailto:jack@suse.cz>; =
mailto:andrea.righi@canonical.com <mailto:andrea.righi@canonical.com>; =
mailto:glen.valante@linaro.org <mailto:glen.valante@linaro.org>; =
mailto:axboe@kernel.dk <mailto:axboe@kernel.dk>; Michael English =
<mailto:michael.english@seagate.com>; Andrew Ring =
<mailto:andrew.ring@seagate.com>; Varun Boddu =
<mailto:varunreddy.boddu@seagate.com>; Damien Le Moal =
<mailto:damien.lemoal@wdc.com>
> Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support =
multi-actuator drives
>=20
>=20
> This message has originated from an External Source. Please use proper =
judgment and caution when opening attachments, clicking links, or =
responding to this email.
>=20
>=20
>> Il giorno 8 set 2022, alle ore 04:46, Rory Chen =
<mailto:rory.c.chen@seagate.com> ha scritto:
>>=20
>> I change the comparison condition and it can eliminate the warning.
>=20
> Yep. The crash you reported also goes away?
>=20
>> <               if (end >=3D iar->sector + 1 && end < iar->sector + =
iar->nr_sectors + 1)
>>>             if (end >=3D iar->sector && end < iar->sector +=20
>>> iar->nr_sectors)
>>=20
>> I don't know if this change is appropriate
>=20
> Unfortunately your change conflicts with the standard code, taken from =
the original patches on access ranges [1].  I've CCed Damien, the author =
of this patch series.
>=20
> [1] =
https://secure-web.cisco.com/12uvPqOwOjHJPiVGM6hJ7791jpWxxy8My3bFD1oA0pNh9=
m0W778f8IM7HPxjRUL8-94N0gKahHwtK-sEv1Tgk2Oo4H9GTAlLoml_uWF6BGktvDAlDp-zdNQ=
UzCL7y1OCz_MJMaNlS5h0iwsE3q9m7tJsCFUWW0YEgcJE6LRTrZDQpFJhG3pGCLFgoPIuKa3o8=
B136dJoQvEtek7ZOQFKqesuZKbu4lvM4ds0HOLs5TIgJR_mSJ8UmhP5_M3a1CaDxdDzQ784H3E=
ydkRN9a6v9-Oogo-wYUqS8fRq35rUyw1t2IblmgJzr6aoGazZsJHxBXPjpxA9DSEQqUtH7oT5R=
GM4qxLpEmYjgyzpJUZqhUCSXye7-lCTIQIB-SGzRuZDVbIqK5tZd3F_YK9LcAN0iVH_qfBM4zR=
e_4w4h5ikJdhc/https%3A%2F%2Flwn.net%2Fml%2Flinux-block%2F20210909023545.11=
01672-2-damien.lemoal%40wdc.com%2F
>=20
> Thanks,
> Paolo
>=20
>> but  bio_end_sector deducting 1 said by Tyler seems to make sense.
>>=20
>> From: Paolo Valente <mailto:paolo.valente@linaro.org>
>> Sent: Thursday, August 25, 2022 10:45 PM
>> To: Tyler Erickson <mailto:tyler.erickson@seagate.com>
>> Cc: Rory Chen <mailto:rory.c.chen@seagate.com>; Arie van der Hoeven=20=

>> <mailto:arie.vanderhoeven@seagate.com>; Muhammad Ahmad=20
>> <mailto:muhammad.ahmad@seagate.com>; =
mailto:linux-block@vger.kernel.org=20
>> <mailto:linux-block@vger.kernel.org>; =
mailto:linux-kernel@vger.kernel.org=20
>> <mailto:linux-kernel@vger.kernel.org>; Jan Kara =
<mailto:jack@suse.cz>;=20
>> mailto:andrea.righi@canonical.com =
<mailto:andrea.righi@canonical.com>;=20
>> mailto:glen.valante@linaro.org <mailto:glen.valante@linaro.org>; =
mailto:axboe@kernel.dk=20
>> <mailto:axboe@kernel.dk>; Michael English =
<mailto:michael.english@seagate.com>;=20
>> Andrew Ring <mailto:andrew.ring@seagate.com>; Varun Boddu=20
>> <mailto:varunreddy.boddu@seagate.com>
>> Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support=20
>> multi-actuator drives
>>=20
>>=20
>> This message has originated from an External Source. Please use =
proper judgment and caution when opening attachments, clicking links, or =
responding to this email.
>>=20
>>=20
>> Hi
>>=20
>>> Il giorno 18 ago 2022, alle ore 17:40, Tyler Erickson =
<mailto:tyler.erickson@seagate.com> ha scritto:
>>>=20
>>> 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, this is an incorrect ending LBA for that actuator. This is =
because LBAs are zero 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 last LBA value for where to issue a final IO read/write to =
account for LBA values 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
>>> 0            1                                               0       =
    17578328064
>>> 1            1                         17578328064           =
17578328064
>>>=20
>>> If using the incorrect formula to get the final LBA for actuator 0, =
you would 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 should be calculated as starting LBA + range - 1.
>>>=20
>>=20
>> Ok
>>=20
>>> I had reached out to Seagate's T10 and T13 representatives for =
clarification and verification and this is most likely what is causing =
the error is a missing - 1 somewhere after getting the information =
reported by the device. They agreed that the reporting from the drive =
and the SCSI to ATA translation is correct.
>>>=20
>>> I'm not sure where this is being read and calculated, but it is not =
an error in the low-level libata or sd level of the kernel. It may be in =
bfq, or it may be in some other place after the sd layer.
>>=20
>> This apparent mistake is in the macro bio_end_sector (defined in=20
>> include/linux/bio.h), which seems to be translated as sector+size.
>> Jens, can you shed a light on this point?
>>=20
>> Thanks,
>> Paolo
>>=20
>>> I know there were some additions to read this and report it up the =
stack, but I did not think those were wrong as they seemed to pass the =
drive reported information up the stack.
>>>=20
>>> Tyler Erickson
>>> Seagate Technology
>>>=20
>>>=20
>>> Seagate Internal
>>>=20
>>> -----Original Message-----
>>> From: Rory Chen <mailto:rory.c.chen@seagate.com>
>>> Sent: Wednesday, August 10, 2022 6:59 AM
>>> To: Paolo Valente <mailto:paolo.valente@linaro.org>
>>> Cc: Arie van der Hoeven <mailto:arie.vanderhoeven@seagate.com>; =
Muhammad=20
>>> Ahmad <mailto:muhammad.ahmad@seagate.com>; =
mailto:linux-block@vger.kernel.org;=20
>>> mailto:linux-kernel@vger.kernel.org; Jan Kara <mailto:jack@suse.cz>;=20=

>>> mailto:andrea.righi@canonical.com; mailto:glen.valante@linaro.org; =
mailto:axboe@kernel.dk;=20
>>> Tyler Erickson <mailto:tyler.erickson@seagate.com>; Michael English=20=

>>> <mailto:michael.english@seagate.com>; Andrew Ring =
<mailto:andrew.ring@seagate.com>;=20
>>> Varun Boddu <mailto:varunreddy.boddu@seagate.com>
>>> Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support=20
>>> multi-actuator drives
>>>=20
>>> The block trace shows the start sector is 35156656120 and transfer =
length is 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 reporting the warning message.
>>> 8,64   7       13     0.039401337 19176  Q  RA 35156656120 + 8 =
[systemd-udevd]
>>> 8,64   7       15     0.039403946 19176  P   N [systemd-udevd]
>>> 8,64   7       16     0.039405132 19176  I  RA 35156656120 + 8 =
[systemd-udevd]
>>> 8,64   7       18     0.039411554 19176  D  RA 35156656120 + 8 =
[systemd-udevd]
>>> 8,64   0       40     0.039479055     0  C  RA 35156656120 + 8 [0]
>>>=20
>>> It may need to know where calculate "bio_end_sector" value as =
35156656128. I have patched libata and sd driver for Dual Actuator.
>>>=20
>>>=20
>>>=20
>>> From: Paolo Valente <mailto:paolo.valente@linaro.org>
>>> Sent: Wednesday, August 10, 2022 6:22 PM
>>> To: Rory Chen <mailto:rory.c.chen@seagate.com>
>>> Cc: Arie van der Hoeven <mailto:arie.vanderhoeven@seagate.com>; =
Muhammad=20
>>> Ahmad <mailto:muhammad.ahmad@seagate.com>; =
mailto:linux-block@vger.kernel.org=20
>>> <mailto:linux-block@vger.kernel.org>; =
mailto:linux-kernel@vger.kernel.org=20
>>> <mailto:linux-kernel@vger.kernel.org>; Jan Kara =
<mailto:jack@suse.cz>;=20
>>> mailto:andrea.righi@canonical.com =
<mailto:andrea.righi@canonical.com>;=20
>>> mailto:glen.valante@linaro.org <mailto:glen.valante@linaro.org>; =
mailto:axboe@kernel.dk=20
>>> <mailto:axboe@kernel.dk>; Tyler Erickson =
<mailto:tyler.erickson@seagate.com>;=20
>>> Michael English <mailto:michael.english@seagate.com>; Andrew Ring=20
>>> <mailto:andrew.ring@seagate.com>; Varun Boddu =
<mailto:varunreddy.boddu@seagate.com>
>>> Subject: Re: [PATCH 0/8] block, bfq: extend bfq to support=20
>>> multi-actuator drives
>>>=20
>>>=20
>>> This message has originated from an External Source. Please use =
proper judgment and caution when opening attachments, clicking links, or =
responding to this email.
>>>=20
>>>=20
>>>> Il giorno 9 ago 2022, alle ore 05:47, Rory Chen =
<mailto:rory.c.chen@seagate.com> ha scritto:
>>>>=20
>>>> 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)
>>>>=20
>>>> Hi Paolo,
>>>>=20
>>>=20
>>> Hi
>>>=20
>>>> I am from Seagate China and face a problem when I'm evaluating the =
bfq patches. Could you please check?
>>>> Thanks
>>>>=20
>>>> Issue statement
>>>> When running performance test on bfq patch, I observed warning =
message "bfq_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 determines 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.
>>>=20
>>> Yep, this sanity check fails if the end sector of a new IO does not =
belong to any sector range.
>>>=20
>>>> I captured the block trace and didn't found request LBA 35156656128 =
instead only found max request LBA 35156656127.
>>>=20
>>> Maybe in the trace you see only start sectors?  The failed check si =
performed on end sectors instead.
>>>=20
>>> At any rate, there seems to be an off-by-one error in the value(s) =
stored in the sector field(s) of the blk_independent_access_range data =
structure.
>>>=20
>>> I guess we may need some help/feedback from people competent on this =
stuff.
>>>=20
>>>> I'm not sure if this warning message is related to later OS hung.
>>>>=20
>>>=20
>>> 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 where we get with this sector error first.
>>>=20
>>> Thank you for testing this extended version of bfq, Paolo
>>>=20
>>>>=20
>>>> 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=20=

>>>> of storage elements:1 starting LBA:0x417c00000 number of=20
>>>> LBAs:0x417c00000 [17578328064]
>>>>=20
>>>>=20
>>>>=20
>>>>=20
>>>>=20
>>>> From: Paolo Valente <mailto:paolo.valente@linaro.org>
>>>> Sent: Thursday, June 23, 2022 8:53 AM
>>>> To: Jens Axboe <mailto:axboe@kernel.dk>
>>>> Cc: mailto:linux-block@vger.kernel.org =
<mailto:linux-block@vger.kernel.org>;=20
>>>> mailto:linux-kernel@vger.kernel.org =
<mailto:linux-kernel@vger.kernel.org>;=20
>>>> mailto:jack@suse.cz <mailto:jack@suse.cz>; =
mailto:andrea.righi@canonical.com=20
>>>> <mailto:andrea.righi@canonical.com>; mailto:glen.valante@linaro.org=20=

>>>> <mailto:glen.valante@linaro.org>; Arie van der Hoeven=20
>>>> <mailto:arie.vanderhoeven@seagate.com>; Paolo Valente=20
>>>> <mailto:paolo.valente@linaro.org>
>>>> Subject: [PATCH 0/8] block, bfq: extend bfq to support=20
>>>> multi-actuator drives
>>>>=20
>>>>=20
>>>> This message has originated from an External Source. Please use =
proper judgment and caution when opening attachments, clicking links, or =
responding to this email.
>>>>=20
>>>>=20
>>>> 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.=20=

>>>> For example, Seagate's Serial Advanced Technology Attachment (SATA)=20=

>>>> version contains two actuators and maps the lower half of the SATA=20=

>>>> LBA space to the lower actuator and the upper half to the upper =
actuator.
>>>>=20
>>>> 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.
>>>>=20
>>>> 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.
>>>>=20
>>>> Thanks,
>>>> Paolo
>>>>=20
>>>> [1]
>>>> =
https://secure-web.cisco.com/1hcxnN1C3h1nW7mby7S66_LE8szirQwbQI0fBpY
>>>> eP=20
>>>> =
rA0GTWfyuQyl0GpZaOn32xMSkNT0BUQWloDHFzZ23aYDZdi8NfdrEFLY9pQDBblIvn08
>>>> LR=20
>>>> =
iTVoIOUC8zWSG_r2PCyLtx3ppZq5cWOib_8azxteRRcbKWGdbLPSqg9hfSJSqltth0By
>>>> LO=20
>>>> =
NHEoI3p3e9QNIn6nVAeQbsT3aOQe-F95XrQvaPrFJXx6RGL9kDXyfkbXIHcdcLBf895g
>>>> YB=20
>>>> =
Fn5S2WjBDQq2kzDzZOlc1HekRUhg0qDQcFY6NydVfrqNfLbpAHAth6KyREscQhVTMVRE
>>>> EV=20
>>>> =
a1b6bQByX6grF5pn3pTIo0lODyfX6yRmcbReSYNfOZ65ZPvp-nH530FQ-5nXoRxFf74W
>>>> IK=20
>>>> =
DrNTALs3xQvg03DH4jLez-T2M9xEu-sfEDAEdTGF7BcnmBW6vrPO4_p3k4/https%3A%
>>>> 2F=20
>>>> =
%2Fwww.linaro.org%2Fblog%2Fbudget-fair-queueing-bfq-linux-io-schedul
>>>> er -optimizations-for-multi-actuator-sata-hard-drives%2F
>>>>=20
>>>> 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:=20
>>>> balance I/O injection among underutilized actuators
>>>>=20
>>>> Federico Gavioli (1):
>>>> block, bfq: retrieve independent access ranges from request queue
>>>>=20
>>>> Paolo Valente (4):
>>>> block, bfq: split sync bfq_queues on a per-actuator basis  block,
>>>> bfq: forbid stable merging of queues associated with different =20
>>>> actuators block, bfq: turn scalar fields into arrays in bfq_io_cq =20=

>>>> block, bfq:
>>>> turn BFQ_NUM_ACTUATORS into BFQ_MAX_ACTUATORS
>>>>=20
>>>> block/bfq-cgroup.c  |  97 +++++----
>>>> block/bfq-iosched.c | 488=20
>>>> +++++++++++++++++++++++++++++---------------
>>>> block/bfq-iosched.h | 149 ++++++++++----
>>>> block/bfq-wf2q.c    |   2 +-
>>>> 4 files changed, 493 insertions(+), 243 deletions(-)
>>>>=20
>>>> --
>>>> 2.20.1
>>>>=20
>>>>=20
>>>> Seagate Internal
>>>>=20
>>>> Seagate Internal
>>>=20
>>> Seagate Internal
>>=20
>> Seagate Internal
>=20
>=20
> Seagate Internal
>=20
> Seagate Internal