[Gluster-users] [Gluster-devel] Need a way to display and flush gluster cache ?

[Niels de Vos]

On Wed, Jul 27, 2016 at 10:29:37AM +0530, Mohammed Rafi K C wrote:
> Thanks for your feedback.
> 
> In fact meta xlator is loaded only on fuse mount, is there any
> particular reason to not to use meta-autoload xltor for nfs server and
> libgfapi ?

I have no idea what the reason could be. Hopefully it is described in
its design or feature page. Unfortunately I could only find this
description, and it looks more user oriented than technical details:

  https://github.com/gluster/glusterfs-specs/blob/master/done/Features/meta.md

Maybe that helps a little, or someone else knows where more info about
it has been written?

Niels


> 
> Regards
> 
> Rafi KC
> 
> On 07/26/2016 04:05 PM, Niels de Vos wrote:
> > On Tue, Jul 26, 2016 at 12:43:56PM +0530, Kaushal M wrote:
> >> On Tue, Jul 26, 2016 at 12:28 PM, Prashanth Pai <ppai at redhat.com> wrote:
> >>> +1 to option (2) which similar to echoing into /proc/sys/vm/drop_caches
> >>>
> >>>  -Prashanth Pai
> >>>
> >>> ----- Original Message -----
> >>>> From: "Mohammed Rafi K C" <rkavunga at redhat.com>
> >>>> To: "gluster-users" <gluster-users at gluster.org>, "Gluster Devel" <gluster-devel at gluster.org>
> >>>> Sent: Tuesday, 26 July, 2016 10:44:15 AM
> >>>> Subject: [Gluster-devel] Need a way to display and flush gluster cache ?
> >>>>
> >>>> Hi,
> >>>>
> >>>> Gluster stack has it's own caching mechanism , mostly on client side.
> >>>> But there is no concrete method to see how much memory are consuming by
> >>>> gluster for caching and if needed there is no way to flush the cache memory.
> >>>>
> >>>> So my first question is, Do we require to implement this two features
> >>>> for gluster cache?
> >>>>
> >>>>
> >>>> If so I would like to discuss some of our thoughts towards it.
> >>>>
> >>>> (If you are not interested in implementation discussion, you can skip
> >>>> this part :)
> >>>>
> >>>> 1) Implement a virtual xattr on root, and on doing setxattr, flush all
> >>>> the cache, and for getxattr we can print the aggregated cache size.
> >>>>
> >>>> 2) Currently in gluster native client support .meta virtual directory to
> >>>> get meta data information as analogues to proc. we can implement a
> >>>> virtual file inside the .meta directory to read  the cache size. Also we
> >>>> can flush the cache using a special write into the file, (similar to
> >>>> echoing into proc file) . This approach may be difficult to implement in
> >>>> other clients.
> >> +1 for making use of the meta-xlator. We should be making more use of it.
> > Indeed, this would be nice. Maybe this can also expose the memory
> > allocations like /proc/slabinfo.
> >
> > The io-stats xlator can dump some statistics to
> > /var/log/glusterfs/samples/ and /var/lib/glusterd/stats/ . That seems to
> > be acceptible too, and allows to get statistics from server-side
> > processes without involving any clients.
> >
> > HTH,
> > Niels
> >
> >
> >>>> 3) A cli command to display and flush the data with ip and port as an
> >>>> argument. GlusterD need to send the op to client from the connected
> >>>> client list. But this approach would be difficult to implement for
> >>>> libgfapi based clients. For me, it doesn't seems to be a good option.
> >>>>
> >>>> Your suggestions and comments are most welcome.
> >>>>
> >>>> Thanks to Talur and Poornima for their suggestions.
> >>>>
> >>>> Regards
> >>>>
> >>>> Rafi KC
> >>>>
> >>>> _______________________________________________
> >>>> Gluster-devel mailing list
> >>>> Gluster-devel at gluster.org
> >>>> http://www.gluster.org/mailman/listinfo/gluster-devel
> >>>>
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