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Message-ID: <20210318020243epcms2p8259fa1d5e99e3c463c6b9e9106693476@epcms2p8>
Date: Thu, 18 Mar 2021 11:02:43 +0900
From: Daejun Park <daejun7.park@...sung.com>
To: Can Guo <cang@...eaurora.org>,
Daejun Park <daejun7.park@...sung.com>
CC: Greg KH <gregkh@...uxfoundation.org>,
"avri.altman@....com" <avri.altman@....com>,
"jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
"martin.petersen@...cle.com" <martin.petersen@...cle.com>,
"asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
"stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
"bvanassche@....org" <bvanassche@....org>,
"huobean@...il.com" <huobean@...il.com>,
ALIM AKHTAR <alim.akhtar@...sung.com>,
"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
"linux-kernel@...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: Re: [PATCH v29 4/4] scsi: ufs: Add HPB 2.0 support
>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.
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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