ms_crc_data false
With 0.93, I tried ceph tell 'osd.*' injectargs '--ms_crc_data=false' '--ms_crc_header=false' and saw the changes reflected in ceph admin-daemon But having done that, perf top still shows time being spent in crc32 routines. Is there some other parameter that needs changing? -- Tom Deneau -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: ms_crc_data false
On Wed, Apr 8, 2015 at 3:38 PM, Deneau, Tom wrote: > With 0.93, I tried > ceph tell 'osd.*' injectargs '--ms_crc_data=false' '--ms_crc_header=false' > > and saw the changes reflected in ceph admin-daemon > > But having done that, perf top still shows time being spent in crc32 routines. > Is there some other parameter that needs changing? You can change this config value, but unfortunately it won't have any effect on a running daemon. You'll need to specify it in a config and restart. -Greg -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: ms_crc_data false
> -Original Message- > From: Sage Weil [mailto:s...@newdream.net] > Sent: Wednesday, April 08, 2015 5:40 PM > To: Deneau, Tom > Cc: ceph-devel > Subject: Re: ms_crc_data false > > On Wed, 8 Apr 2015, Deneau, Tom wrote: > > With 0.93, I tried > > ceph tell 'osd.*' injectargs '--ms_crc_data=false' '-- > ms_crc_header=false' > > > > and saw the changes reflected in ceph admin-daemon > > > > But having done that, perf top still shows time being spent in crc32 > routines. > > Is there some other parameter that needs changing? > > The osd still does a CRC for the purposes of write journaling. This can't be > disabled currently. You shouldn't see this come up on reads... > > sage Hmm, I am doing rados bench seq so only reads. Is this in 0.93 or do I need 0.94? -- Tom -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: ms_crc_data false
> -Original Message-
> From: Gregory Farnum [mailto:g...@gregs42.com]
> Sent: Wednesday, April 08, 2015 6:26 PM
> To: Deneau, Tom
> Cc: ceph-devel
> Subject: Re: ms_crc_data false
>
> On Wed, Apr 8, 2015 at 3:38 PM, Deneau, Tom wrote:
> > With 0.93, I tried
> > ceph tell 'osd.*' injectargs '--ms_crc_data=false' '--
> ms_crc_header=false'
> >
> > and saw the changes reflected in ceph admin-daemon
> >
> > But having done that, perf top still shows time being spent in crc32
> routines.
> > Is there some other parameter that needs changing?
>
> You can change this config value, but unfortunately it won't have any effect
> on a running daemon. You'll need to specify it in a config and restart.
> -Greg
Thanks, Greg.
Here are some observations on my single node system
after changing the ceph.conf and restarting all daemons...
loop rados bench seq reading 4M objects (1 thread) (dropping caches before each
invocation)
* BW went up with ms crc xxx = false
* but still see signficant crc32 line attributed to ceph-osd
* no writes happening
* note: with ms crc xxx = true, there were 2 crc32 lines in perf top, the
2nd
one attributed to librados, that one is gone with ms crc xxx = false
loop rados get single largeObject (1.6G) /dev/null (dropping caches before each
invocation)
* no change in BW from ms crc xxx = true
* no crc32 line in perf top
* whereas with ms crc xxx=true there were 2 lines one for ceph-osd, one
for librados
-- Tom Deneau
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Re: ms_crc_data false
On Wed, 8 Apr 2015, Deneau, Tom wrote: > With 0.93, I tried > ceph tell 'osd.*' injectargs '--ms_crc_data=false' '--ms_crc_header=false' > > and saw the changes reflected in ceph admin-daemon > > But having done that, perf top still shows time being spent in crc32 routines. > Is there some other parameter that needs changing? The osd still does a CRC for the purposes of write journaling. This can't be disabled currently. You shouldn't see this come up on reads... sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
