Re: can't get bache's sequential_cutoff to work

[Stefan Priebe <s.priebe-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>]

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
>>     --
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