fopen() may fail and it does not check its return vaule here,
it is better to dump op count to the normal log file.

Signed-off-by: Li Liu <john.liuli@huawei.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>