答复: 答复: 回复: [External Mail]Re: [PATCH v2] mm/cma: print total and used count in cma_alloc()

[高翔 <gaoxiang17@xiaomi.com>]

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________________________________
发件人: Andrew Morton <akpm@linux-foundation.org>
发送时间: 2024年10月11日 5:17
收件人: 高翔
抄送: Frank van der Linden; David Hildenbrand; Xiang Gao; linux-mm@kvack.org; linux-kernel@vger.kernel.org
主题: Re: 答复: 回复: [External Mail]Re: [PATCH v2] mm/cma: print total and used count in cma_alloc()

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On Thu, 10 Oct 2024 08:48:55 +0000 高翔 <gaoxiang17@xiaomi.com> wrote:

>
> ________________________________
> 发件人: Frank van der Linden <fvdl@google.com>
> 发送时间: 2024年10月5日 6:55
> 收件人: Andrew Morton
> 抄送: 高翔; David Hildenbrand; Xiang Gao; linux-mm@kvack.org; linux-kernel@vger.kernel.org
> 主题: Re: 回复: [External Mail]Re: [PATCH v2] mm/cma: print total and used count in cma_alloc()
>
> [外部邮件] 此邮件来源于小米公司外部，请谨慎处理。若对邮件安全性存疑，请将邮件转发给misec@xiaomi.com进行反馈
>
> On Fri, Oct 4, 2024 at 3:39 PM Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> > On Fri, 4 Oct 2024 12:23:30 +0000 高翔 <gaoxiang17@xiaomi.com> wrote:
> >
> > > > > +static unsigned long cma_get_used_pages(struct cma *cma) {
> > > > > +     unsigned long used;
> > > > > +
> > > > > +     spin_lock_irq(&cma->lock);
> > > > > +     used = bitmap_weight(cma->bitmap, (int)cma_bitmap_maxno(cma));
> > > > > +     spin_unlock_irq(&cma->lock);
> > > >
> > > > This adds overhead to each allocation, even if debug outputs are
> > > > ignored I assume?
> > > >
> > > > I wonder if we'd want to print these details only when our allocation
> > > > failed?
> > > >
> > > > Alternatively, we could actually track how many pages are allocated in
> > > > the cma, so we don't have to traverse the complete bitmap on every
> > > > allocation.
> > > >
> > >
> > > Yep, that's what I did as part of
> > > https://lore.kernel.org/all/20240724124845.614c03ad39f8af3729cebee6@linux-foundation.org/T/
> > >
> > > That patch didn't make it in (yet). I'm happy for it to be combined with this one if that's easier.
> >
> > That patch has been forgotten about.  As I asked in July,
> > "I suggest a resend, and add some Cc:s for likely reviewers."
>
> > Indeed - I certainly wasn't suggesting that anyone else forgot about
> > it, it's up to me to follow up here, and I haven't yet.
>
>
> Do I need to resend it after adding "used_count" member to the "struct cma" as V3?

> I don't know what is being asked here.  What is this used_count?  Some
> other patch, presumably?  Which?

> The preferable thing to do is to send a patch against latest
> mm-unstable or linux-next.

OK.

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