Re: [PATCH 0/1] ipc/util.{c,h}: Use binary search for max_idx

[Davidlohr Bueso]

On Sun, 25 Apr 2021, Manfred Spraul wrote:

> 2nd version of the patch:
> @Andrew: Could you add the patch to your mm tree, as candidate for
> linux-next?
>
> Note:
> I have tried to remove the ids->max_idx cache entirely. Unfortunately,
> this causes a significant slow-down of semstat(,,IPC_STAT):
>   * no object allocated, no ipcmni_extended: +50%
>   * no object allocated, with ipcmni_extended: +80%
>   * 30 objects allocated, with large gaps, no ipcmni_extended:
>           +350%
> Thus I haven't removed ids->max_id.

Right, IPC_STAT is the main usecase for max_id. But I'm not sure why
you were looking to remove it in the first place - or was it just to
avoid this patch altogether?

Thanks,
Davidlohr