* can't get bache's sequential_cutoff to work
@ 2013-07-23 14:16 Stefan Priebe - Profihost AG
[not found] ` <CA+res+Ti1-tGANkb9wRAgF4sAcUqEv9RfGjDvbdX3bbxS=XK8g@mail.gmail.com>
0 siblings, 1 reply; 6+ messages in thread
From: Stefan Priebe - Profihost AG @ 2013-07-23 14:16 UTC (permalink / raw)
To: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; +Cc: Kent Overstreet
Hi,
maybe i missed something or maybe i'm just wrong.
# cat /sys/block/bcache2/bcache/sequential_cutoff
512k
# cat /sys/block/bcache2/bcache/stats_five_minute/bypassed
64.3M
# dd if=/dev/zero of=/mnt/bcache2/ttt bs=4M count=1000 oflag=direct
1000+0 records in
1000+0 records out
4194304000 bytes (4,2 GB) copied, 11,0348 s, 380 MB/s
# cat /sys/block/bcache2/bcache/stats_five_minute/bypassed
69.3M
I also see only IOP/s an writes go to the SSD but not to the disk
behind. What's wrong?
Greets,
Stefan
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: can't get bache's sequential_cutoff to work
[not found] ` <CA+res+Ti1-tGANkb9wRAgF4sAcUqEv9RfGjDvbdX3bbxS=XK8g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
@ 2013-07-23 19:41 ` Stefan Priebe
[not found] ` <51EEDC73.5020101-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: Stefan Priebe @ 2013-07-23 19:41 UTC (permalink / raw)
To: Jack Wang
Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Kent Overstreet
It's 3.10 with bcache Updates from kent's for 3.10 branch.
Stefan
This mail was sent with my iPhone.
Am 23.07.2013 um 18:00 schrieb Jack Wang <jack.wang.usish-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<mailto:jack.wang.usish-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>>:
> Hi Stefan,
>
> Strange, I tested bcache 2 month ago, mostly bcache-3.2 branch in
> writeback mode, it works as claimed.
>
> which kernel version are you using?
>
> Jack
>
>
> 2013/7/23 Stefan Priebe - Profihost AG <s.priebe-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org
> <mailto:s.priebe-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>>
>
> Hi,
>
> maybe i missed something or maybe i'm just wrong.
>
>
> # cat /sys/block/bcache2/bcache/sequential_cutoff
> 512k
>
> # cat /sys/block/bcache2/bcache/stats_five_minute/bypassed
> 64.3M
>
> # dd if=/dev/zero of=/mnt/bcache2/ttt bs=4M count=1000 oflag=direct
> 1000+0 records in
> 1000+0 records out
> 4194304000 bytes (4,2 GB) copied, 11,0348 s, 380 MB/s
>
> # cat /sys/block/bcache2/bcache/stats_five_minute/bypassed
> 69.3M
>
> I also see only IOP/s an writes go to the SSD but not to the disk
> behind. What's wrong?
>
> Greets,
> Stefan
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-bcache" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> <mailto:majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: can't get bache's sequential_cutoff to work
[not found] ` <51EEDC73.5020101-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>
@ 2013-07-23 20:31 ` Stefan Priebe
[not found] ` <51EEE805.7090200-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: Stefan Priebe @ 2013-07-23 20:31 UTC (permalink / raw)
To: Jack Wang
Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Kent Overstreet
It works fine if do really small block writes like this:
# dd if=/dev/zero of=/dev/bcache0 bs=100 count=5000000
Can anybody tell me why?
Stefan
Am 23.07.2013 21:41, schrieb Stefan Priebe:
> It's 3.10 with bcache Updates from kent's for 3.10 branch.
>
> Stefan
>
> This mail was sent with my iPhone.
>
> Am 23.07.2013 um 18:00 schrieb Jack Wang <jack.wang.usish-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
> <mailto:jack.wang.usish-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>>:
>
>> Hi Stefan,
>>
>> Strange, I tested bcache 2 month ago, mostly bcache-3.2 branch in
>> writeback mode, it works as claimed.
>>
>> which kernel version are you using?
>>
>> Jack
>>
>>
>> 2013/7/23 Stefan Priebe - Profihost AG <s.priebe-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org
>> <mailto:s.priebe-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>>
>>
>> Hi,
>>
>> maybe i missed something or maybe i'm just wrong.
>>
>>
>> # cat /sys/block/bcache2/bcache/sequential_cutoff
>> 512k
>>
>> # cat /sys/block/bcache2/bcache/stats_five_minute/bypassed
>> 64.3M
>>
>> # dd if=/dev/zero of=/mnt/bcache2/ttt bs=4M count=1000 oflag=direct
>> 1000+0 records in
>> 1000+0 records out
>> 4194304000 bytes (4,2 GB) copied, 11,0348 s, 380 MB/s
>>
>> # cat /sys/block/bcache2/bcache/stats_five_minute/bypassed
>> 69.3M
>>
>> I also see only IOP/s an writes go to the SSD but not to the disk
>> behind. What's wrong?
>>
>> Greets,
>> Stefan
>> --
>> To unsubscribe from this list: send the line "unsubscribe
>> linux-bcache" in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> <mailto:majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
>>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: can't get bache's sequential_cutoff to work
[not found] ` <51EEE805.7090200-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>
@ 2013-07-23 20:38 ` Stefan Priebe
[not found] ` <51EEE9D9.7090207-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>
0 siblings, 1 reply; 6+ messages in thread
From: Stefan Priebe @ 2013-07-23 20:38 UTC (permalink / raw)
To: Jack Wang
Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Kent Overstreet
Mhm works directly on block device but not with XFS on top.
Am 23.07.2013 22:31, schrieb Stefan Priebe:
> It works fine if do really small block writes like this:
>
> # dd if=/dev/zero of=/dev/bcache0 bs=100 count=5000000
>
> Can anybody tell me why?
>
> Stefan
> Am 23.07.2013 21:41, schrieb Stefan Priebe:
>> It's 3.10 with bcache Updates from kent's for 3.10 branch.
>>
>> Stefan
>>
>> This mail was sent with my iPhone.
>>
>> Am 23.07.2013 um 18:00 schrieb Jack Wang <jack.wang.usish-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
>> <mailto:jack.wang.usish-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>>:
>>
>>> Hi Stefan,
>>>
>>> Strange, I tested bcache 2 month ago, mostly bcache-3.2 branch in
>>> writeback mode, it works as claimed.
>>>
>>> which kernel version are you using?
>>>
>>> Jack
>>>
>>>
>>> 2013/7/23 Stefan Priebe - Profihost AG <s.priebe-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org
>>> <mailto:s.priebe-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>>
>>>
>>> Hi,
>>>
>>> maybe i missed something or maybe i'm just wrong.
>>>
>>>
>>> # cat /sys/block/bcache2/bcache/sequential_cutoff
>>> 512k
>>>
>>> # cat /sys/block/bcache2/bcache/stats_five_minute/bypassed
>>> 64.3M
>>>
>>> # dd if=/dev/zero of=/mnt/bcache2/ttt bs=4M count=1000 oflag=direct
>>> 1000+0 records in
>>> 1000+0 records out
>>> 4194304000 bytes (4,2 GB) copied, 11,0348 s, 380 MB/s
>>>
>>> # cat /sys/block/bcache2/bcache/stats_five_minute/bypassed
>>> 69.3M
>>>
>>> I also see only IOP/s an writes go to the SSD but not to the disk
>>> behind. What's wrong?
>>>
>>> Greets,
>>> Stefan
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe
>>> linux-bcache" in
>>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>> <mailto:majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>
>>>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: can't get bache's sequential_cutoff to work
[not found] ` <51EEE9D9.7090207-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>
@ 2013-07-25 0:14 ` Kent Overstreet
2013-07-25 7:17 ` Stefan Priebe - Profihost AG
0 siblings, 1 reply; 6+ messages in thread
From: Kent Overstreet @ 2013-07-25 0:14 UTC (permalink / raw)
To: Stefan Priebe
Cc: Jack Wang, linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
On Tue, Jul 23, 2013 at 10:38:49PM +0200, Stefan Priebe wrote:
> Mhm works directly on block device but not with XFS on top.
That's odd...
Do you suppose you could look at what blktrace says is going down? If
you could compare what blktrace says is going to the bcache device with
and without XFS, hopefully that'll show what's going wrong...
Only thing I can think of that would cause it is for some reason XFS is
sending bios down in the wrong order... which normally wouldn't be _too_
painful since both the elevator and the disk's cache will reorder the
IOs, so I can see how that would slip by.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: can't get bache's sequential_cutoff to work
2013-07-25 0:14 ` Kent Overstreet
@ 2013-07-25 7:17 ` Stefan Priebe - Profihost AG
0 siblings, 0 replies; 6+ messages in thread
From: Stefan Priebe - Profihost AG @ 2013-07-25 7:17 UTC (permalink / raw)
To: Kent Overstreet
Cc: Jack Wang, linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Am 25.07.2013 02:14, schrieb Kent Overstreet:
> On Tue, Jul 23, 2013 at 10:38:49PM +0200, Stefan Priebe wrote:
>> Mhm works directly on block device but not with XFS on top.
>
> That's odd...
>
> Do you suppose you could look at what blktrace says is going down? If
> you could compare what blktrace says is going to the bcache device with
> and without XFS, hopefully that'll show what's going wrong...
>
> Only thing I can think of that would cause it is for some reason XFS is
> sending bios down in the wrong order... which normally wouldn't be _too_
> painful since both the elevator and the disk's cache will reorder the
> IOs, so I can see how that would slip by.
Hi,
will try to have a look. But can it also be that the history of 128
entries is too small under my workload and bcache does not detect the
sequence? Is there a way to try with a higher value like 1024?
Stefan
^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-07-23 14:16 can't get bache's sequential_cutoff to work Stefan Priebe - Profihost AG
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2013-07-23 19:41 ` Stefan Priebe
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2013-07-23 20:31 ` Stefan Priebe
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2013-07-23 20:38 ` Stefan Priebe
[not found] ` <51EEE9D9.7090207-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>
2013-07-25 0:14 ` Kent Overstreet
2013-07-25 7:17 ` Stefan Priebe - Profihost AG
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