Re: [PATCH v29 4/4] scsi: ufs: Add HPB 2.0 support
From: Can Guo
Date: Thu Mar 18 2021 - 00:50:49 EST
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@xxxxxxxxxxx>
---
+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;
+}
+