Hi Raghavendra, i'll try to gather the information you need, hopefully this weekend. One thing i've done this week: deactivate performance.quick-read (https://bugzilla.redhat.com/show_bug.cgi?id=1673058), which (according to munin) ended in a massive drop in network traffic and a slightly lower iowait. Maybe that has helped already. We'll see. performance.nl-cache is deactivated due to unreadable files/directories; we have a highly concurrent workload. There are some nginx backend webservers that check if a requested file exists in the glusterfs filesystem; i counted the log entries, this can be up to 5 million entries a day; about 2/3 of the files are found in the filesystem, they get delivered to the frontend; if not: the nginx's send the request via round robin to 3 backend tomcats, and they have to check whether a directory exists or not (and then create it and the requested files). So it happens that tomcatA creates a directory and a file in it, and within (milli)seconds tomcatB+C create additional files in this dir. Deactivating nl-cache helped to solve this issue, after having conversation with Nithya and Ravishankar. Just wanted to explain that. Thx so far, Hubert Am Fr., 29. März 2019 um 06:29 Uhr schrieb Raghavendra Gowdappa <rgowdapp@xxxxxxxxxx>: > > +Gluster-users > > Sorry about the delay. There is nothing suspicious about per thread CPU utilization of glusterfs process. However looking at the volume profile attached I see huge number of lookups. I think if we cutdown the number of lookups probably we'll see improvements in performance. I need following information: > > * dump of fuse traffic under heavy load (use --dump-fuse option while mounting) > * client volume profile for the duration of heavy load - https://docs.gluster.org/en/latest/Administrator%20Guide/Performance%20Testing/ > * corresponding brick volume profile > > Basically I need to find out > * whether these lookups are on existing files or non-existent files > * whether they are on directories or files > * why/whether md-cache or kernel attribute cache or nl-cache will help to cut down lookups. > > regards, > Raghavendra > > On Mon, Mar 25, 2019 at 12:13 PM Hu Bert <revirii@xxxxxxxxxxxxxx> wrote: >> >> Hi Raghavendra, >> >> sorry, this took a while. The last weeks the weather was bad -> less >> traffic, but this weekend there was a massive peak. I made 3 profiles >> with top, but at first look there's nothing special here. >> >> I also made a gluster profile (on one of the servers) at a later >> moment. Maybe that helps. I also added some munin graphics from 2 of >> the clients and 1 graphic of server network, just to show how massive >> the problem is. >> >> Just wondering if the high io wait is related to the high network >> traffic bug (https://bugzilla.redhat.com/show_bug.cgi?id=1673058); if >> so, i could deactivate performance.quick-read and check if there is >> less iowait. If that helps: wonderful - and yearningly awaiting >> updated packages (e.g. v5.6). If not: maybe we have to switch from our >> normal 10TB hdds (raid10) to SSDs if the problem is based on slow >> hardware in the use case of small files (images). >> >> >> Thx, >> Hubert >> >> Am Mo., 4. März 2019 um 16:59 Uhr schrieb Raghavendra Gowdappa >> <rgowdapp@xxxxxxxxxx>: >> > >> > Were you seeing high Io-wait when you captured the top output? I guess not as you mentioned the load increases during weekend. Please note that this data has to be captured when you are experiencing problems. >> > >> > On Mon, Mar 4, 2019 at 8:02 PM Hu Bert <revirii@xxxxxxxxxxxxxx> wrote: >> >> >> >> Hi, >> >> sending the link directly to you and not the list, you can distribute >> >> if necessary. the command ran for about half a minute. Is that enough? >> >> More? Less? >> >> >> >> https://download.outdooractive.com/top.output.tar.gz >> >> >> >> Am Mo., 4. März 2019 um 15:21 Uhr schrieb Raghavendra Gowdappa >> >> <rgowdapp@xxxxxxxxxx>: >> >> > >> >> > >> >> > >> >> > On Mon, Mar 4, 2019 at 7:47 PM Raghavendra Gowdappa <rgowdapp@xxxxxxxxxx> wrote: >> >> >> >> >> >> >> >> >> >> >> >> On Mon, Mar 4, 2019 at 4:26 PM Hu Bert <revirii@xxxxxxxxxxxxxx> wrote: >> >> >>> >> >> >>> Hi Raghavendra, >> >> >>> >> >> >>> at the moment iowait and cpu consumption is quite low, the main >> >> >>> problems appear during the weekend (high traffic, especially on >> >> >>> sunday), so either we have to wait until next sunday or use a time >> >> >>> machine ;-) >> >> >>> >> >> >>> I made a screenshot of top (https://abload.de/img/top-hvvjt2.jpg) and >> >> >>> a text output (https://pastebin.com/TkTWnqxt), maybe that helps. Seems >> >> >>> like processes like glfs_fuseproc (>204h) and glfs_epoll (64h for each >> >> >>> process) consume a lot of CPU (uptime 24 days). Is that already >> >> >>> helpful? >> >> >> >> >> >> >> >> >> Not much. The TIME field just says the amount of time the thread has been executing. Since its a long standing mount, we can expect such large values. But, the value itself doesn't indicate whether the thread itself was overloaded at any (some) interval(s). >> >> >> >> >> >> Can you please collect output of following command and send back the collected data? >> >> >> >> >> >> # top -bHd 3 > top.output >> >> > >> >> > >> >> > Please collect this on problematic mounts and bricks. >> >> > >> >> >> >> >> >>> >> >> >>> >> >> >>> Hubert >> >> >>> >> >> >>> Am Mo., 4. März 2019 um 11:31 Uhr schrieb Raghavendra Gowdappa >> >> >>> <rgowdapp@xxxxxxxxxx>: >> >> >>> > >> >> >>> > what is the per thread CPU usage like on these clients? With highly concurrent workloads we've seen single thread that reads requests from /dev/fuse (fuse reader thread) becoming bottleneck. Would like to know what is the cpu usage of this thread looks like (you can use top -H). >> >> >>> > >> >> >>> > On Mon, Mar 4, 2019 at 3:39 PM Hu Bert <revirii@xxxxxxxxxxxxxx> wrote: >> >> >>> >> >> >> >>> >> Good morning, >> >> >>> >> >> >> >>> >> we use gluster v5.3 (replicate with 3 servers, 2 volumes, raid10 as >> >> >>> >> brick) with at the moment 10 clients; 3 of them do heavy I/O >> >> >>> >> operations (apache tomcats, read+write of (small) images). These 3 >> >> >>> >> clients have a quite high I/O wait (stats from yesterday) as can be >> >> >>> >> seen here: >> >> >>> >> >> >> >>> >> client: https://abload.de/img/client1-cpu-dayulkza.png >> >> >>> >> server: https://abload.de/img/server1-cpu-dayayjdq.png >> >> >>> >> >> >> >>> >> The iowait in the graphics differ a lot. I checked netstat for the >> >> >>> >> different clients; the other clients have 8 open connections: >> >> >>> >> https://pastebin.com/bSN5fXwc >> >> >>> >> >> >> >>> >> 4 for each server and each volume. The 3 clients with the heavy I/O >> >> >>> >> have (at the moment) according to netstat 170, 139 and 153 >> >> >>> >> connections. An example for one client can be found here: >> >> >>> >> https://pastebin.com/2zfWXASZ >> >> >>> >> >> >> >>> >> gluster volume info: https://pastebin.com/13LXPhmd >> >> >>> >> gluster volume status: https://pastebin.com/cYFnWjUJ >> >> >>> >> >> >> >>> >> I just was wondering if the iowait is based on the clients and their >> >> >>> >> workflow: requesting a lot of files (up to hundreds per second), >> >> >>> >> opening a lot of connections and the servers aren't able to answer >> >> >>> >> properly. Maybe something can be tuned here? >> >> >>> >> >> >> >>> >> Especially the server|client.event-threads (both set to 4) and >> >> >>> >> performance.(high|normal|low|least)-prio-threads (all at default value >> >> >>> >> 16) and performance.io-thread-count (32) options, maybe these aren't >> >> >>> >> properly configured for up to 170 client connections. >> >> >>> >> >> >> >>> >> Both servers and clients have a Xeon CPU (6 cores, 12 threads), a 10 >> >> >>> >> GBit connection and 128G (servers) respectively 256G (clients) RAM. >> >> >>> >> Enough power :-) >> >> >>> >> >> >> >>> >> >> >> >>> >> Thx for reading && best regards, >> >> >>> >> >> >> >>> >> Hubert >> >> >>> >> _______________________________________________ >> >> >>> >> Gluster-users mailing list >> >> >>> >> Gluster-users@xxxxxxxxxxx >> >> >>> >> https://lists.gluster.org/mailman/listinfo/gluster-users _______________________________________________ Gluster-users mailing list Gluster-users@xxxxxxxxxxx https://lists.gluster.org/mailman/listinfo/gluster-users
