On Mon, Aug 02, 2021 at 01:20:13PM +1000, Nicholas Piggin wrote:
> This counter tracks the number of watches a user has, to compare against
> the 'max_user_watches' limit. This causes a scalability bottleneck on
> SPECjbb2015 on large systems as there is only one user. Changing to a
> per-cpu counter increases throughput of the benchmark by about 30% on a
> 16-socket, > 1000 thread system.
>
> Reported-by: Anton Blanchard <anton@xxxxxxxxxx>
> Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
With all tinyconfig builds (and all other builds with CONFIG_EPOLL=n),
this patch results in:
kernel/user.c: In function 'free_user':
kernel/user.c:141:35: error: 'struct user_struct' has no member named 'epoll_watches'
141 | percpu_counter_destroy(&up->epoll_watches);
| ^~
kernel/user.c: In function 'alloc_uid':
kernel/user.c:189:45: error: 'struct user_struct' has no member named 'epoll_watches'
189 | if (percpu_counter_init(&new->epoll_watches, 0, GFP_KERNEL)) {
| ^~
kernel/user.c:203:52: error: 'struct user_struct' has no member named 'epoll_watches'
203 | percpu_counter_destroy(&new->epoll_watches);
| ^~
kernel/user.c: In function 'uid_cache_init':
kernel/user.c:225:43: error: 'struct user_struct' has no member named 'epoll_watches'
225 | if (percpu_counter_init(&root_user.epoll_watches, 0, GFP_KERNEL))
| ^
Guenter
