在 2022/5/20 上午12:12, Alexei Starovoitov 写道:
On Wed, May 18, 2022 at 8:12 PM Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx> wrote:
在 2022/5/19 上午4:39, Yonghong Song 写道:
On 5/17/22 11:57 PM, Feng Zhou wrote:
在 2022/5/18 下午2:32, Alexei Starovoitov 写道:
On Tue, May 17, 2022 at 11:27 PM Feng zhou
<zhoufeng.zf@xxxxxxxxxxxxx> wrote:
From: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
We encountered bad case on big system with 96 CPUs that
alloc_htab_elem() would last for 1ms. The reason is that after the
prealloc hashtab has no free elems, when trying to update, it will
still
grab spin_locks of all cpus. If there are multiple update users, the
competition is very serious.
So this patch add is_empty in pcpu_freelist_head to check freelist
having free or not. If having, grab spin_lock, or check next cpu's
freelist.
Before patch: hash_map performance
./map_perf_test 1
could you explain what parameter '1' means here?
This code is here:
samples/bpf/map_perf_test_user.c
samples/bpf/map_perf_test_kern.c
parameter '1' means testcase flag, test hash_map's performance
parameter '2048' means test hash_map's performance when free=0.
testcase flag '2048' is added by myself to reproduce the problem phenomenon.
Please convert it to selftests/bpf/bench,
so that everyone can reproduce the issue you're seeing
and can assess whether it's a real issue or a corner case.
Also please avoid adding indent in the patch.
Instead of
if (!s->extralist.is_empty) {
.. churn
do
if (s->extralist.is_empty)
Ok, will do. Thanks.
