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Thu, 17 Apr 2025 02:51:48 +0000 (UTC) Date: Thu, 17 Apr 2025 10:51:44 +0800 From: Baoquan He To: Uladzislau Rezki Cc: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/5] mm/vmalloc.c: optimize code in decay_va_pool_node() a little bit Message-ID: References: <20250415023952.27850-1-bhe@redhat.com> <20250415023952.27850-4-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Rspamd-Queue-Id: 6086F4000A X-Stat-Signature: nrnwzije64uadyiqrtet7ret9bfoh9qw X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1744858317-777386 X-HE-Meta: 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 GvJGiYri bs3hY366X0G/twoGb/oOLvwQGDwOEr7HsNln8mIh8mNy5yluA2c9UqTto4EN5DWT3IcXu6mkWQuXYEvn1YJLwxFBVdSP02mcQpqgdOMLZPxu7xh8PHrpaiNhPodGYlw0nUbWsRMFDb2OSpekW0gPCy3KMdPa4KUxdjpw0CYwrfK0GRd1yBfN2B9mgw6sqg/d7P84Lc0ldJAug7sW6pJCgXr7+yQE+iFYisezaYBgnCkYld3t0kcwkp9EHXdLg3J+F788YN4ZhHf8+s/U6RDdEJc8MqSf0ByxjuU/JDSqGs/4H7znXvABiPdl7cCM48t6VjwBYdvtuOVBg2/ukogjwafzEpGnutnahOS7+k/AeLfcLGxnsKmOKiQaasIMmva9xanbhtMntNmQPwc8pLdj0T0WLn9SagVzGU5aWdodNMRZNho+oVKlhO9OmyzgBfy86ZT/kvxPmec9jRzmIO2sfauW1kiXFo0lFS+vp 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 04/16/25 at 03:50pm, Uladzislau Rezki wrote: > On Tue, Apr 15, 2025 at 10:39:50AM +0800, Baoquan He wrote: > > When purge lazily freed vmap areas, VA stored in vn->pool[] will also be > > taken away into free vmap tree partially or completely accordingly, that > > is done in decay_va_pool_node(). When doing that, for each pool of node, > > the whole list is detached from the pool for handling. At this time, > > that pool is empty. It's not necessary to update the pool size each time > > when one VA is removed and addded into free vmap tree. > > > > Here change code to update the pool size when attaching the pool back. > > > > Signed-off-by: Baoquan He > > --- > > mm/vmalloc.c | 23 +++++++++++------------ > > 1 file changed, 11 insertions(+), 12 deletions(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index 488d69b56765..bf735c890878 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -2150,7 +2150,7 @@ decay_va_pool_node(struct vmap_node *vn, bool full_decay) > > LIST_HEAD(decay_list); > > struct rb_root decay_root = RB_ROOT; > > struct vmap_area *va, *nva; > > - unsigned long n_decay; > > + unsigned long n_decay, len; > > int i; > > > > for (i = 0; i < MAX_VA_SIZE_PAGES; i++) { > > @@ -2164,22 +2164,20 @@ decay_va_pool_node(struct vmap_node *vn, bool full_decay) > > list_replace_init(&vn->pool[i].head, &tmp_list); > > spin_unlock(&vn->pool_lock); > > > > - if (full_decay) > > - WRITE_ONCE(vn->pool[i].len, 0); > > + len = n_decay = vn->pool[i].len; > > + WRITE_ONCE(vn->pool[i].len, 0); > > > > /* Decay a pool by ~25% out of left objects. */ > > - n_decay = vn->pool[i].len >> 2; > > + if (!full_decay) > > + n_decay >>= 2; > > + len -= n_decay; > > > > list_for_each_entry_safe(va, nva, &tmp_list, list) { > > + if (!n_decay) > > + break; > > list_del_init(&va->list); > > merge_or_add_vmap_area(va, &decay_root, &decay_list); > > - > > - if (!full_decay) { > > - WRITE_ONCE(vn->pool[i].len, vn->pool[i].len - 1); > > - > > - if (!--n_decay) > > - break; > > - } > > + n_decay--; > > } > > > > /* > > @@ -2188,9 +2186,10 @@ decay_va_pool_node(struct vmap_node *vn, bool full_decay) > > * can populate the pool therefore a simple list replace > > * operation takes place here. > > */ > > - if (!full_decay && !list_empty(&tmp_list)) { > > + if (!list_empty(&tmp_list)) { > > spin_lock(&vn->pool_lock); > > list_replace_init(&tmp_list, &vn->pool[i].head); > > + vn->pool[i].len = len; > > spin_unlock(&vn->pool_lock); > > } > > } > > -- > > 2.41.0 > > > Which Linux version this patch is based on? I can not apply it. I can apply them on the latest mainline kernel, next/master and mm-new branch of akpm/mm.git. I checked just now. > > Small nits: > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index c909b8fea6eb..0ae53c997219 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2150,7 +2150,7 @@ decay_va_pool_node(struct vmap_node *vn, bool full_decay) > LIST_HEAD(decay_list); > struct rb_root decay_root = RB_ROOT; > struct vmap_area *va, *nva; > - unsigned long n_decay, len; > + unsigned long n_decay, pool_len; > int i; > > for (i = 0; i < MAX_VA_SIZE_PAGES; i++) { > @@ -2164,21 +2164,20 @@ decay_va_pool_node(struct vmap_node *vn, bool full_decay) > list_replace_init(&vn->pool[i].head, &tmp_list); > spin_unlock(&vn->pool_lock); > > - len = n_decay = vn->pool[i].len; > + pool_len = n_decay = vn->pool[i].len; > WRITE_ONCE(vn->pool[i].len, 0); > > /* Decay a pool by ~25% out of left objects. */ > if (!full_decay) > n_decay >>= 2; > - len -= n_decay; > + pool_len -= n_decay; > > list_for_each_entry_safe(va, nva, &tmp_list, list) { > - if (!n_decay) > + if (!n_decay--) > break; > > list_del_init(&va->list); > merge_or_add_vmap_area(va, &decay_root, &decay_list); > - n_decay--; > } > > /* > @@ -2190,7 +2189,7 @@ decay_va_pool_node(struct vmap_node *vn, bool full_decay) > if (!list_empty(&tmp_list)) { > spin_lock(&vn->pool_lock); > list_replace_init(&tmp_list, &vn->pool[i].head); > - vn->pool[i].len = len; > + vn->pool[i].len = pool_len; > spin_unlock(&vn->pool_lock); > } > } > > > on top of this? > > a) decay in "if" statement, no need extra line; > b) rename len to something obvious - pool_len. All look good, will add them to this patch 3 of v2. Thanks a lot.