share_pool: Optimize compact procedure

ascend inclusion
category: perf
bugzilla: https://gitee.com/openeuler/kernel/issues/I4EUVI


CVE: NA

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We did an compaction experiment on Hi1951. First creating external
fragmentation, then echo 1 > /proc/sys/vm/compact_memory.

Fragmentation size | 0G   | 2G   | 4G  | 8G
Compaction time(s) | 0.07 | 0.85 | 1.7 | 3.4

Obviously, sysctl_compaction_handler has a big performance impact.

We optimize share pool compact procedure as follows:
1. At most one compact daemon is allowed.
2. Creating a compact daemon is only allowed when the last one is
finished at least *sysctl_sp_compact_interval* seconds ago.

Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Reviewed-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>