lkml.org 
[lkml]   [2019]   [Feb]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRe: [PATCH V2] lightnvm: pblk: prevent stall due to wb threshold
Date

> On 31 Jan 2019, at 21.10, Hans Holmberg <hans@owltronix.com> wrote:
>
> On Thu, Jan 31, 2019 at 5:33 PM Javier González <javier@javigon.com> wrote:
>>> On 31 Jan 2019, at 11.41, Hans Holmberg <hans@owltronix.com> wrote:
>>>
>>> Hi Javier!
>>>
>>> How did you test this? I'm trying to add a test case to our testing framework.
>>>
>>> This is what i ran in qemu, and I got a hang (with this version of the patch)
>>>
>>> nvme lnvm create -d nvme0n1 -t pblk -n pblk0 -f -b 0 -e 0
>>
>> I run several low configurations without problem. Can you share the qemu configuration and version?
>
> Of course!
>
> qemu remote: https://github.com/CNEX-Labs/qemu-nvme.git
> branch: master (cb200e3ccf9c1ff21f6275c6cb68b2801135a640)
>
> My geometry:
> parallel units: 8, secs per chk: 768, meta size 16, ws min 12, ws opt
> 24, cunits=0

You are right, lmw_cunits=0 gives the problem.

What about the following? If it goes through cijoe, I'll send a V3.

diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c
index d4ca8c64ee0f..a6133b50ed9c 100644
--- a/drivers/lightnvm/pblk-rb.c
+++ b/drivers/lightnvm/pblk-rb.c
@@ -45,10 +45,23 @@ void pblk_rb_free(struct pblk_rb *rb)
/*
* pblk_rb_calculate_size -- calculate the size of the write buffer
*/
-static unsigned int pblk_rb_calculate_size(unsigned int nr_entries)
+static unsigned int pblk_rb_calculate_size(unsigned int nr_entries,
+ unsigned int threshold)
{
- /* Alloc a write buffer that can at least fit 128 entries */
- return (1 << max(get_count_order(nr_entries), 7));
+ unsigned int thr_sz = 1 << (get_count_order(threshold + NVM_MAX_VLBA));
+ unsigned int max_sz = max(thr_sz, nr_entries);
+ unsigned int max_io;
+
+ /* Alloc a write buffer that can (i) fit at least two split bios
+ * (considering max I/O size NVM_MAX_VLBA, and (ii) guarantee that the
+ * threshold will be respected
+ */
+ max_io = (1 << max((int)(get_count_order(max_sz)),
+ (int)(get_count_order(NVM_MAX_VLBA << 1))));
+ if ((threshold + NVM_MAX_VLBA) >= max_io)
+ max_io <<= 1;
+
+ return max_io;
}

/*
@@ -67,12 +80,12 @@ int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int threshold,
unsigned int alloc_order, order, iter;
unsigned int nr_entries;

- nr_entries = pblk_rb_calculate_size(size);
+ nr_entries = pblk_rb_calculate_size(size, threshold);
entries = vzalloc(array_size(nr_entries, sizeof(struct pblk_rb_entry)));
if (!entries)
return -ENOMEM;

- power_size = get_count_order(size);
+ power_size = get_count_order(nr_entries);
power_seg_sz = get_count_order(seg_size);

down_write(&pblk_rb_lock);
@@ -149,7 +162,7 @@ int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int threshold,
* Initialize rate-limiter, which controls access to the write buffer
* by user and GC I/O
*/
- pblk_rl_init(&pblk->rl, rb->nr_entries);
+ pblk_rl_init(&pblk->rl, rb->nr_entries, threshold);

return 0;
}
diff --git a/drivers/lightnvm/pblk-rl.c b/drivers/lightnvm/pblk-rl.c
index 76116d5f78e4..b014957dde0b 100644
--- a/drivers/lightnvm/pblk-rl.c
+++ b/drivers/lightnvm/pblk-rl.c
@@ -207,7 +207,7 @@ void pblk_rl_free(struct pblk_rl *rl)
del_timer(&rl->u_timer);
}

-void pblk_rl_init(struct pblk_rl *rl, int budget)
+void pblk_rl_init(struct pblk_rl *rl, int budget, int threshold)
{
struct pblk *pblk = container_of(rl, struct pblk, rl);
struct nvm_tgt_dev *dev = pblk->dev;
@@ -217,7 +217,6 @@ void pblk_rl_init(struct pblk_rl *rl, int budget)
int sec_meta, blk_meta;
unsigned int rb_windows;

-
/* Consider sectors used for metadata */
sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;
blk_meta = DIV_ROUND_UP(sec_meta, geo->clba);
@@ -234,7 +233,7 @@ void pblk_rl_init(struct pblk_rl *rl, int budget)
/* To start with, all buffer is available to user I/O writers */
rl->rb_budget = budget;
rl->rb_user_max = budget;
- rl->rb_max_io = budget >> 1;
+ rl->rb_max_io = threshold ? (budget - threshold) : (budget - 1);
rl->rb_gc_max = 0;
rl->rb_state = PBLK_RL_HIGH;

diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 72ae8755764e..a6386d5acd73 100644
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -924,7 +924,7 @@ int pblk_gc_sysfs_force(struct pblk *pblk, int force);
/*
* pblk rate limiter
*/
-void pblk_rl_init(struct pblk_rl *rl, int budget);
+void pblk_rl_init(struct pblk_rl *rl, int budget, int threshold);
void pblk_rl_free(struct pblk_rl *rl);
void pblk_rl_update_rates(struct pblk_rl *rl);
int pblk_rl_high_thrs(struct pblk_rl *rl);
--
2.17.1
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2019-02-04 09:15    [W:0.096 / U:0.104 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site