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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