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

[Mohammed Rafi K C]

On 07/28/2016 07:56 PM, Niels de Vos wrote:
> On Thu, Jul 28, 2016 at 05:58:15PM +0530, Mohammed Rafi K C wrote:
>>
>> On 07/27/2016 04:33 PM, Raghavendra G wrote:
>>>
>>> On Wed, Jul 27, 2016 at 10:29 AM, Mohammed Rafi K C
>>> <rkavunga at redhat.com <mailto:rkavunga at redhat.com>> 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 think its because of lack of resources. I am not aware of any
>>> technical reason for not using on NFSv3 server and gfapi.
>> Cool. I will try to see how we can implement meta-autoliad feature for
>> nfs-server and libgfapi. Once we have the feature in place, I will
>> implement the cache memory display/flush feature using meta xlators.
> In case you plan to have this ready in a month (before the end of
> August), you should propose it as a 3.9 feature. Click the "Edir this
> page on GitHub" link on the bottom of
> https://www.gluster.org/community/roadmap/3.9/ :)
I will do an assessment and will see if I can spend some time on this
for 3.9 release. If so, I will add it into 3.9 feature page.

Regards
Rafi KC

>
> Thanks,
> Niels
>
>
>> Thanks for your valuable feedback.
>> Rafi KC
>>
>>>  
>>>
>>>     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> <mailto: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> <mailto:rkavunga at redhat.com>
>>>>>>>     To: "gluster-users" <gluster-users at gluster.org> <mailto:gluster-users at gluster.org>, "Gluster Devel" <gluster-devel at gluster.org> <mailto: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
>>>>>>>
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>>>
>>>
>>> -- 
>>> Raghavendra G