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charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Stat-Signature: 6a9rhtqsnd56iqdqpeumh1h5gji8gi55 X-Rspam-User: X-Rspamd-Queue-Id: B5558C0009 X-Rspamd-Server: rspam08 X-HE-Tag: 1744760503-554318 X-HE-Meta: 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 OI9g4gni 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04/15/25 at 05:25pm, Uladzislau Rezki wrote: > On Tue, Apr 15, 2025 at 10:39:49AM +0800, Baoquan He wrote: > > When finding VA in vn->busy, if VA spans several zones and the passed > > addr is not the same as va->va_start, we should scan the vn in reverse > > odrdr because the starting address of VA must be smaller than the passed > > addr if it really resides in the VA. > > > > E.g on a system nr_vmap_nodes=100, > > > > <----va----> > > -|-----|-----|-----|-----|-----|-----|-----|-----|-----|- > > ... n-1 n n+1 n+2 ... 100 0 1 > > > > VA resides in node 'n' whereas it spans 'n', 'n+1' and 'n+2'. If passed > > addr is within 'n+2', we should try nodes backwards on 'n+1' and 'n', > > then succeed very soon. > > > > Meanwhile we still need loop around because VA could spans node from 'n' > > to node 100, node 0, node 1. > > > > Anyway, changing to find in reverse order can improve efficiency on > > many CPUs system. > > > > Signed-off-by: Baoquan He > > --- > > mm/vmalloc.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index aca1905d3397..488d69b56765 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -2436,7 +2436,7 @@ struct vmap_area *find_vmap_area(unsigned long addr) > > > > if (va) > > return va; > > - } while ((i = (i + 1) % nr_vmap_nodes) != j); > > + } while ((i = (i + nr_vmap_nodes - 1) % nr_vmap_nodes) != j); > > > > return NULL; > > } > > @@ -2462,7 +2462,7 @@ static struct vmap_area *find_unlink_vmap_area(unsigned long addr) > > > > if (va) > > return va; > > - } while ((i = (i + 1) % nr_vmap_nodes) != j); > > + } while ((i = (i + nr_vmap_nodes - 1) % nr_vmap_nodes) != j); > > > > return NULL; > > } > > -- > > 2.41.0 > > > It depends. Consider a below situation: > > addr > | > VA V > <------------> > <---|---|---|---|---|---|---|---> > 0 1 2 3 0 1 2 3 > > basically it matters how big VA and how many nodes it spans. But i > agree that an assumption to reverse back is more convinced in most > cases. Agree, on small system with few CPUs and big VA case, the advantage is not apparent. > > Reviewed-by: Uladzislau Rezki (Sony) Thanks.