Thank you guys,
I tried to add option "exec_prerun=echo 3 > /proc/sys/vm/drop_caches" as well as "exec_prerun=echo 3 | sudo tee /proc/sys/vm/drop_caches", but despite FIO corresponds that command was executed, there are no changes.
But, I caught very strange another behavior. If I will run my FIO test (speaking about 3G file case) twice, after the first run FIO will create my file and print a lot of IOps as described already, but if- before second run- drop cache (by root echo 3 > /proc/sys/vm/drop_caches) I broke will end with broken MDS:
--- begin dump of recent events ---
0> 2017-02-03 02:34:41.974639 7f7e8ec5e700 -1 *** Caught signal (Aborted) **
in thread 7f7e8ec5e700 thread_name:ms_dispatch
ceph version 10.2.4-211-g12b091b (12b091b4a40947aa43919e71a318ed0dcedc8734)
1: (()+0x5142a2) [0x557c51e092a2]
2: (()+0x10b00) [0x7f7e95df2b00]
3: (gsignal()+0x37) [0x7f7e93ccb8d7]
4: (abort()+0x13a) [0x7f7e93ccccaa]
5: (ceph::__ceph_assert_fail(char const*, char const*, int, char const*)+0x265) [0x557c51f133d5]
6: (MutationImpl::~MutationImpl()+0x28e) [0x557c51bb9e1e]
7: (std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release()+0x39) [0x557c51b2ccf9]
8: (Locker::check_inode_max_size(CInode*, bool, bool, unsigned long, bool, unsigned long, utime_t)+0x9a7) [0x557c51ca2757]
9: (Locker::remove_client_cap(CInode*, client_t)+0xb1) [0x557c51ca38f1]
10: (Locker::_do_cap_release(client_t, inodeno_t, unsigned long, unsigned int, unsigned int)+0x90d) [0x557c51ca424d]
11: (Locker::handle_client_cap_release(MClientCapRelease*)+0x1cc) [0x557c51ca449c]
12: (MDSRank::handle_deferrable_message(Message*)+0xc1c) [0x557c51b33d3c]
13: (MDSRank::_dispatch(Message*, bool)+0x1e1) [0x557c51b3c991]
14: (MDSRankDispatcher::ms_dispatch(Message*)+0x15) [0x557c51b3dae5]
15: (MDSDaemon::ms_dispatch(Message*)+0xc3) [0x557c51b25703]
16: (DispatchQueue::entry()+0x78b) [0x557c5200d06b]
17: (DispatchQueue::DispatchThread::entry()+0xd) [0x557c51ee5dcd]
18: (()+0x8734) [0x7f7e95dea734]
19: (clone()+0x6d) [0x7f7e93d80d3d]
NOTE: a copy of the executable, or `objdump -rdS <executable>` is needed to interpret this.
"
On Thu, Feb 2, 2017 at 9:30 PM, Shinobu Kinjo <skinjo@xxxxxxxxxx> wrote:
You may want to add this in your FIO recipe.
* exec_prerun=echo 3 > /proc/sys/vm/drop_caches
Regards,
On Fri, Feb 3, 2017 at 12:36 AM, Wido den Hollander <wido@xxxxxxxx> wrote:
>
>> Op 2 februari 2017 om 15:35 schreef Ahmed Khuraidah <abushihab@xxxxxxxxx>:
>>
>>
>> Hi all,
>>
>> I am still confused about my CephFS sandbox.
>>
>> When I am performing simple FIO test into single file with size of 3G I
>> have too many IOps:
>>
>> cephnode:~ # fio payloadrandread64k3G
>> test: (g=0): rw=randread, bs=64K-64K/64K-64K/64K-64K, ioengine=libaio,
>> iodepth=2
>> fio-2.13
>> Starting 1 process
>> test: Laying out IO file(s) (1 file(s) / 3072MB)
>> Jobs: 1 (f=1): [r(1)] [100.0% done] [277.8MB/0KB/0KB /s] [4444/0/0 iops]
>> [eta 00m:00s]
>> test: (groupid=0, jobs=1): err= 0: pid=3714: Thu Feb 2 07:07:01 2017
>> read : io=3072.0MB, bw=181101KB/s, iops=2829, runt= 17370msec
>> slat (usec): min=4, max=386, avg=12.49, stdev= 6.90
>> clat (usec): min=202, max=5673.5K, avg=690.81, stdev=361
>>
>>
>> But if I will change size to file to 320G, looks like I skip the cache:
>>
>> cephnode:~ # fio payloadrandread64k320G
>> test: (g=0): rw=randread, bs=64K-64K/64K-64K/64K-64K, ioengine=libaio,
>> iodepth=2
>> fio-2.13
>> Starting 1 process
>> Jobs: 1 (f=1): [r(1)] [100.0% done] [4740KB/0KB/0KB /s] [74/0/0 iops] [eta
>> 00m:00s]
>> test: (groupid=0, jobs=1): err= 0: pid=3624: Thu Feb 2 06:51:09 2017
>> read : io=3410.9MB, bw=11641KB/s, iops=181, runt=300033msec
>> slat (usec): min=4, max=442, avg=14.43, stdev=10.07
>> clat (usec): min=98, max=286265, avg=10976.32, stdev=14904.82
>>
>>
>> For random write test such behavior not exists, there are almost the same
>> results - around 100 IOps.
>>
>> So my question: could please somebody clarify where this caching likely
>> happens and how to manage it?
>>
>
> The page cache of your kernel. The kernel will cache the file in memory and perform read operations from there.
>
> Best way is to reboot your client between test runs. Although you can drop kernel caches I always reboot to make sure nothing is cached locally.
>
> Wido
>
>> P.S.
>> This is latest SLES/Jewel based onenode setup which has:
>> 1 MON, 1 MDS (both data and metadata pools on SATA drive) and 1 OSD (XFS on
>> SATA and journal on SSD).
>> My FIO config file:
>> direct=1
>> buffered=0
>> ioengine=libaio
>> iodepth=2
>> runtime=300
>>
>> Thanks
>> _______________________________________________
>> ceph-users mailing list
>> ceph-users@xxxxxxxxxxxxxx
>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph. com
> _______________________________________________
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