* 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[parent not found: <CA+res+Ti1-tGANkb9wRAgF4sAcUqEv9RfGjDvbdX3bbxS=XK8g@mail.gmail.com>]
[parent not found: <CA+res+Ti1-tGANkb9wRAgF4sAcUqEv9RfGjDvbdX3bbxS=XK8g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>]
* 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
[parent not found: <51EEDC73.5020101-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>]
* 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
[parent not found: <51EEE805.7090200-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>]
* 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
[parent not found: <51EEE9D9.7090207-2Lf/h1ldwEHR5kwTpVNS9A@public.gmane.org>]
* 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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[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>
2013-07-23 20:31 ` Stefan Priebe
[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>
2013-07-25 0:14 ` Kent Overstreet
2013-07-25 7:17 ` Stefan Priebe - Profihost AG
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