To add another data point, switched to ceph-fuse 12.2.0, still seeing
lots of lookup.
lookup avg 1892
mkdir avg 367
create avg 222
open avg 228
2017-10-21 2:09 GMT+08:00 Xiaoxi Chen <superdebuger@xxxxxxxxx>:
> @Zheng, my kernel doesn't even has c3f4688a08f. But 200fd27 ("ceph:
> use lookup request to revalidate dentry") is there.
>
> 2017-10-21 0:54 GMT+08:00 Xiaoxi Chen <superdebuger@xxxxxxxxx>:
>> Thanks, will check.
>>
>> A general question, does cephfs kernel client drop dentries/inode
>> cache aggressively? What I know is if MDS issue
>> CEPH_SESSION_RECALL_STATE, client will drop, but is there other cases
>> client will drop cache?
>>
>>
>>
>> 2017-10-20 16:39 GMT+08:00 Yan, Zheng <ukernel@xxxxxxxxx>:
>>> On Fri, Oct 20, 2017 at 3:28 PM, Xiaoxi Chen <superdebuger@xxxxxxxxx> wrote:
>>>> Centos 7.3, kernel version 3.10.0-514.26.2.el7.x86_64.
>>>>
>>>> I extract the logical of file creation in our workload into a
>>>> reproducer , like below.
>>>>
>>>> Concurrently run the reproducer in 2+ node can see a lots of lookup OP.
>>>> I thought the lookup is to open the directory tree so I tried to
>>>> pre-make most of the dirs , use ls -i trying to read the dentries and
>>>> cache it, then re-run the reproducer, seems nothing different..
>>>>
>>>> #include <sys/stat.h>
>>>> #include <fcntl.h>
>>>> int create_file(char * base, int count, int max, int depth)
>>>> {
>>>> int i;
>>>> for(i=0; i<count; i++) {
>>>> char dir[256];
>>>> int mydir = rand() % max;
>>>> sprintf(dir, "%s/%d", path, mydir);
>>>> if (depth >=1) {
>>>> mkdir(dir,0777);
>>>> create_dir(dir, count, max, depth - 1);
>>>> } else {
>>>> int fd = open(dir, O_CREAT | O_EXCL| O_WRONLY , 0666);
>>>> printf("opened path : %s = %d\n", path, fd);
>>>> close(fd);
>>>> }
>>>> }
>>>> }
>>>> int main(int argc, char argv[])
>>>> {
>>>> char path[256];
>>>> while(1) {
>>>> create_file("/import/SQL01", 1, 4 ,10);
>>>> }
>>>> }
>>>>
>>>
>>> still don't see this behavior on 4.13 kernel. I suspect there is
>>> something wrong with dentry lease. please check if your kernel
>>> include:
>>>
>>> commit c3f4688a08f (ceph: don't set req->r_locked_dir in ceph_d_revalidate)
>>> commit 5eb9f6040f3 (ceph: do a LOOKUP in d_revalidate instead of GETATTR)
>>>
>>> The first commit can cause this issue, the second one fixes it.
>>>
>>> Regards
>>> Yan, Zheng
>>>
>>>>
>>>>
>>>> 2017-10-20 10:55 GMT+08:00 Yan, Zheng <ukernel@xxxxxxxxx>:
>>>>> On Fri, Oct 20, 2017 at 12:49 AM, Xiaoxi Chen <superdebuger@xxxxxxxxx> wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I am seeing a lot of lookup request when doing recursive mkdir.
>>>>>> The workload behavior is like:
>>>>>> mkdir DIR0
>>>>>> mkdir DIR0/DIR1
>>>>>> mkdir DIR0/DIR1/DIR2
>>>>>> ....
>>>>>> mkdir DIR0/DIR1/DIR2......./DIR7
>>>>>> create DIR0/DIR1/DIR2......./DIR7/FILE1
>>>>>>
>>>>>> and concurrently run on 50+ clients, the dir name in different
>>>>>> clients may or maynot be the same.
>>>>>>
>>>>>> from the admin socket I was seeing ~50K create requests, but
>>>>>> got 400K lookup requests. The lookup eat up most of the mds capability
>>>>>> so file create is slow.
>>>>>>
>>>>>> Where is the lookup comes from and can we have anyway to
>>>>>> optimize it out ?
>>>>>>
>>>>>
>>>>> I don't see this behavior when running following commands in 4.13
>>>>> kernel client and luminous version ceph-fuse. which client do you use?
>>>>>
>>>>> mkdir d1
>>>>> mkdir d1/d2
>>>>> mkdir d1/d2/d3
>>>>> mkdir d1/d2/d3/d4/
>>>>> mkdir d1/d2/d3/d4/d5
>>>>> touch d1/d2/d3/d4/d5/f
>>>>>
>>>>>> Xiaoxi
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