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Date: Thu, 18 Mar 2021 12:49:33 +0800
From: Can Guo <cang@...eaurora.org>
To: daejun7.park@...sung.com
Cc: Greg KH <gregkh@...uxfoundation.org>, avri.altman@....com,
jejb@...ux.ibm.com, martin.petersen@...cle.com,
asutoshd@...eaurora.org, stanley.chu@...iatek.com,
bvanassche@....org, huobean@...il.com,
ALIM AKHTAR <alim.akhtar@...sung.com>,
linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
JinHwan Park <jh.i.park@...sung.com>,
Javier Gonzalez <javier.gonz@...sung.com>,
SEUNGUK SHIN <seunguk.shin@...sung.com>,
Sung-Jun Park <sungjun07.park@...sung.com>,
Jinyoung CHOI <j-young.choi@...sung.com>,
BoRam Shin <boram.shin@...sung.com>
Subject: Re: [PATCH v29 4/4] scsi: ufs: Add HPB 2.0 support
On 2021-03-18 10:02, Daejun Park wrote:
>> On 2021-03-17 09:42, Daejun Park wrote:
>>>> On 2021-03-15 15:23, Can Guo wrote:
>>>>> On 2021-03-15 15:07, Daejun Park wrote:
>>>>>>>> This patch supports the HPB 2.0.
>>>>>>>>
>>>>>>>> The HPB 2.0 supports read of varying sizes from 4KB to 512KB.
>>>>>>>> In the case of Read (<= 32KB) is supported as single HPB read.
>>>>>>>> In the case of Read (36KB ~ 512KB) is supported by as a
>>>>>>>> combination
>>>>>>>> of
>>>>>>>> write buffer command and HPB read command to deliver more PPN.
>>>>>>>> The write buffer commands may not be issued immediately due to
>>>>>>>> busy
>>>>>>>> tags.
>>>>>>>> To use HPB read more aggressively, the driver can requeue the
>>>>>>>> write
>>>>>>>> buffer
>>>>>>>> command. The requeue threshold is implemented as timeout and can
>>>>>>>> be
>>>>>>>> modified with requeue_timeout_ms entry in sysfs.
>>>>>>>>
>>>>>>>> Signed-off-by: Daejun Park <daejun7.park@...sung.com>
>>>>>>>> ---
>>>>>>>> +static struct attribute *hpb_dev_param_attrs[] = {
>>>>>>>> + &dev_attr_requeue_timeout_ms.attr,
>>>>>>>> + NULL,
>>>>>>>> +};
>>>>>>>> +
>>>>>>>> +struct attribute_group ufs_sysfs_hpb_param_group = {
>>>>>>>> + .name = "hpb_param_sysfs",
>>>>>>>> + .attrs = hpb_dev_param_attrs,
>>>>>>>> +};
>>>>>>>> +
>>>>>>>> +static int ufshpb_pre_req_mempool_init(struct ufshpb_lu *hpb)
>>>>>>>> +{
>>>>>>>> + struct ufshpb_req *pre_req = NULL;
>>>>>>>> + int qd = hpb->sdev_ufs_lu->queue_depth / 2;
>>>>>>>> + int i, j;
>>>>>>>> +
>>>>>>>> + INIT_LIST_HEAD(&hpb->lh_pre_req_free);
>>>>>>>> +
>>>>>>>> + hpb->pre_req = kcalloc(qd, sizeof(struct ufshpb_req),
>>>>>>>> GFP_KERNEL);
>>>>>>>> + hpb->throttle_pre_req = qd;
>>>>>>>> + hpb->num_inflight_pre_req = 0;
>>>>>>>> +
>>>>>>>> + if (!hpb->pre_req)
>>>>>>>> + goto release_mem;
>>>>>>>> +
>>>>>>>> + for (i = 0; i < qd; i++) {
>>>>>>>> + pre_req = hpb->pre_req + i;
>>>>>>>> + INIT_LIST_HEAD(&pre_req->list_req);
>>>>>>>> + pre_req->req = NULL;
>>>>>>>> + pre_req->bio = NULL;
>>>>>>>
>>>>>>> Why don't prepare bio as same as wb.m_page? Won't that save more
>>>>>>> time
>>>>>>> for ufshpb_issue_pre_req()?
>>>>>>
>>>>>> It is pre_req pool. So although we prepare bio at this time, it
>>>>>> just
>>>>>> only for first pre_req.
>>>>>
>>>>> I meant removing the bio_alloc() in ufshpb_issue_pre_req() and
>>>>> bio_put()
>>>>> in ufshpb_pre_req_compl_fn(). bios, in pre_req's case, just hold a
>>>>> page.
>>>>> So, prepare 16 (if queue depth is 32) bios here, just use them
>>>>> along
>>>>> with
>>>>> wb.m_page and call bio_reset() in ufshpb_pre_req_compl_fn(). Shall
>>>>> it
>>>>> work?
>>>>>
>>>>
>>>> If it works, you can even have the bio_add_pc_page() called here.
>>>> Later
>>>> in
>>>> ufshpb_execute_pre_req(), you don't need to call
>>>> ufshpb_pre_req_add_bio_page(),
>>>> just call ufshpb_prep_entry() once instead - it save many repeated
>>>> steps
>>>> for a
>>>> pre_req, and you don't even need to call bio_reset() in this case,
>>>> since
>>>> for a
>>>> bio, nothing changes after it is binded with a specific page...
>>>
>>> Hi, Can Guo
>>>
>>> I tried the idea that you suggested, but it doesn't work properly.
>>> This optimization should be done next time for enhancement.
>>
>> Can you elaborate please? Any error seen?
>>
>> Per my understanding, in the case for pre_reqs, a bio is no different
>> from a page. Here it can reserve 16 pages for later use, which can be
>> done the same for bios.
>
> I found some problem with re-using pre allocated bio.
>
> The following kernel message is related with problem.
> [ 2.750530] ------------[ cut here ]------------
> [ 2.751404] WARNING: CPU: 4 PID: 170 at
> drivers/scsi/scsi_lib.c:1020 scsi_alloc_sgtables+0x253/0x2b0
> [ 2.753054] Modules linked in:
> [ 2.753651] CPU: 4 PID: 170 Comm: mount Not tainted 5.12.0-rc1+ #331
> [ 2.754752] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
> [ 2.756813] RIP: 0010:scsi_alloc_sgtables+0x253/0x2b0
> [ 2.757699] Code: 85 c0 74 19 41 0f b6 44 24 18 8d 50 e0 83 fa 03
> 76 30 41 bd 01 00 00 00 e9 1f fe ff ff be 01 00 00 00 45 31 ed e9 19
> fe ff ff <0f> 0b b8 0a f
> [ 2.761021] RSP: 0018:ffffb06e0027f538 EFLAGS: 00010246
> [ 2.761902] RAX: 0000000000000000 RBX: ffff9c3a42d424d0 RCX:
> ffffb06e0027f5e0
> [ 2.763184] RDX: ffff9c3a42d426a8 RSI: 0000000000000000 RDI:
> ffff9c3a42d424d0
> [ 2.764446] RBP: ffffb06e0027f570 R08: 0000000000000000 R09:
> 0000000000000000
> [ 2.765704] R10: ffffffff8eb0dda0 R11: 00000000fffb7675 R12:
> ffff9c3a42d423c0
> [ 2.766976] R13: 0000000000000000 R14: ffff9c3a41bed000 R15:
> ffff9c3a420f4000
> [ 2.768225] FS: 00007f42d1eab100(0000) GS:ffff9c3b77c00000(0000)
> knlGS:0000000000000000
> [ 2.769666] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 2.770719] CR2: 00007f42d1ac1000 CR3: 0000000104bee006 CR4:
> 0000000000370ee0
> [ 2.771997] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [ 2.773288] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
> 0000000000000400
> [ 2.774543] Call Trace:
> [ 2.775092] scsi_queue_rq+0x9b6/0xb20
> [ 2.775754] __blk_mq_try_issue_directly+0x150/0x1f0
> [ 2.776636] blk_mq_request_issue_directly+0x49/0x80
> [ 2.777616] blk_insert_cloned_request+0x85/0xd0
> [ 2.778470] ufshpb_prep.cold+0x793/0x7be
> [ 2.779179] ufshcd_queuecommand+0x114/0x690
> [ 2.779986] scsi_queue_rq+0x38a/0xb20
> [ 2.780755] blk_mq_dispatch_rq_list+0x13d/0x760
> [ 2.781605] ? dd_dispatch_request+0x67/0x1c0
> [ 2.782337] __blk_mq_do_dispatch_sched+0xb5/0x2c0
> [ 2.783291] __blk_mq_sched_dispatch_requests+0x13c/0x180
> [ 2.784209] blk_mq_sched_dispatch_requests+0x30/0x60
> [ 2.785195] __blk_mq_run_hw_queue+0x49/0x90
> [ 2.786024] __blk_mq_delay_run_hw_queue+0x162/0x180
> [ 2.786890] blk_mq_run_hw_queue+0x85/0xe0
> [ 2.787590] blk_mq_sched_insert_requests+0xdf/0x2b0
> [ 2.788558] blk_mq_flush_plug_list+0x118/0x240
> [ 2.789405] blk_flush_plug_list+0xde/0x110
> [ 2.790225] blk_finish_plug+0x21/0x30
> [ 2.790878] read_pages+0x16a/0x1d0
> [ 2.791534] page_cache_ra_unbounded+0x123/0x1c0
> [ 2.792392] do_page_cache_ra+0x38/0x40
> [ 2.793183] force_page_cache_ra+0x97/0x110
> [ 2.793875] page_cache_sync_ra+0x26/0x50
> [ 2.794671] filemap_get_pages+0xc8/0x4b0
> [ 2.795482] filemap_read+0xc9/0x340
> [ 2.796144] ? find_held_lock+0x31/0x90
> [ 2.796809] generic_file_read_iter+0xcc/0x130
> [ 2.797644] blkdev_read_iter+0x30/0x40
> [ 2.798436] new_sync_read+0x10e/0x190
> [ 2.799112] vfs_read+0x178/0x1d0
> [ 2.799732] ksys_read+0x6b/0xf0
> [ 2.800361] __x64_sys_read+0x15/0x20
> [ 2.801027] do_syscall_64+0x38/0x50
> [ 2.801770] entry_SYSCALL_64_after_hwframe+0x44/0xae
> [ 2.802655] RIP: 0033:0x7f42d209a461
> [ 2.803313] Code: fe ff ff 50 48 8d 3d fe d0 09 00 e8 e9 03 02 00
> 66 0f 1f 84 00 00 00 00 00 48 8d 05 99 62 0d 00 8b 00 85 c0 75 13 31
> c0 0f 05 <48> 3d 00 f0 8
> [ 2.806632] RSP: 002b:00007ffe7b88bc88 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000000
> [ 2.807942] RAX: ffffffffffffffda RBX: 000055ccb2e070d0 RCX:
> 00007f42d209a461
> [ 2.809218] RDX: 0000000000040000 RSI: 00007f42d1ac1038 RDI:
> 0000000000000004
> [ 2.810482] RBP: 000055ccb2e07120 R08: 00007f42d1ac1010 R09:
> 0000000000000000
> [ 2.811729] R10: 0000000000000022 R11: 0000000000000246 R12:
> 0000003b95fc0000
> [ 2.813005] R13: 0000000000040000 R14: 00007f42d1ac1028 R15:
> 00007f42d1ac1010
> [ 2.814276] irq event stamp: 9319
> [ 2.814868] hardirqs last enabled at (9327): [<ffffffff8c4d2033>]
> console_unlock+0x4d3/0x5e0
> [ 2.816349] hardirqs last disabled at (9336): [<ffffffff8c4d1fa6>]
> console_unlock+0x446/0x5e0
> [ 2.817837] softirqs last enabled at (8674): [<ffffffff8d4002ec>]
> __do_softirq+0x2ec/0x40f
> [ 2.819298] softirqs last disabled at (8669): [<ffffffff8c46ad9e>]
> irq_exit_rcu+0xae/0xb0
> [ 2.820744] ---[ end trace af3986a7787eeecf ]---
>
> It is related to bi_iter value of bio is changed after use it.
Understood the problem now, let's take the 1st way -
1. prepare bios in ufshpb_pre_req_mempool_init() (leave
bio_add_pc_page() where it was)
2. call bio_reset() in ufshpb_put_pre_req()
This should work.
Thanks,
Can Guo.
>
> Thanks,
> Daejun
>
>> This is not an enhancement, but a doubt - why not? Unless it is not
>> doable.
>>
>> Thanks,
>> Can Guo.
>>
>>>
>>> Thanks
>>> Daejun
>>>
>>>> Can Guo.
>>>>
>>>>> Thanks,
>>>>> Can Guo.
>>>>>
>>>>>> After use it, it should be prepared bio at issue phase.
>>>>>>
>>>>>> Thanks,
>>>>>> Daejun
>>>>>>
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Can Guo.
>>>>>>>
>>>>>>>> +
>>>>>>>> + pre_req->wb.m_page = alloc_page(GFP_KERNEL |
>>>>>>>> __GFP_ZERO);
>>>>>>>> + if (!pre_req->wb.m_page) {
>>>>>>>> + for (j = 0; j < i; j++)
>>>>>>>> +
>>>>>>>> __free_page(hpb->pre_req[j].wb.m_page);
>>>>>>>> +
>>>>>>>> + goto release_mem;
>>>>>>>> + }
>>>>>>>> + list_add_tail(&pre_req->list_req,
>>>>>>>> &hpb->lh_pre_req_free);
>>>>>>>> + }
>>>>>>>> +
>>>>>>>> + return 0;
>>>>>>>> +release_mem:
>>>>>>>> + kfree(hpb->pre_req);
>>>>>>>> + return -ENOMEM;
>>>>>>>> +}
>>>>>>>> +
>>>>>>>
>>>>>>>
>>>>>>>
>>>>
>>>>
>>>>
>>
>>
>>
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