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Bottomley" , Alexander Lobakin , Alexander Shishkin , Alexey Klimov , Andrea Merello , Andy Shevchenko , Arnaldo Carvalho de Melo , Arnd Bergmann , Ben Gardon , Benjamin Herrenschmidt , Brian Cain , Catalin Marinas , Christoph Lameter , Daniel Bristot de Oliveira , David Hildenbrand , Dennis Zhou , Geert Uytterhoeven , Heiko Carstens , Ian Rogers , Ingo Molnar , Jaegeuk Kim , Jakub Kicinski , Jiri Olsa , Joe Perches , Jonas Bonn , Leo Yan , Mark Rutland , Namhyung Kim , Palmer Dabbelt , Paolo Bonzini , Peter Xu , Peter Zijlstra , Petr Mladek , Rasmus Villemoes , Rich Felker , Samuel Mendoza-Jonas , Sean Christopherson , Sergey Senozhatsky , Shuah Khan , Stefan Kristiansson , Steven Rostedt , Tejun Heo , Thomas Bogendoerfer , Ulf Hansson , Will Deacon , Wolfram Sang , Yoshinori Sato , Yury Norov Subject: [PATCH 14/17] mm/percpu: micro-optimize pcpu_is_populated() Date: Sat, 14 Aug 2021 14:17:10 -0700 Message-Id: <20210814211713.180533-15-yury.norov@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210814211713.180533-1-yury.norov@gmail.com> References: <20210814211713.180533-1-yury.norov@gmail.com> MIME-Version: 1.0 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=WMJpwYfq; spf=pass (imf05.hostedemail.com: domain of yurynorov@gmail.com designates 209.85.214.181 as permitted sender) smtp.mailfrom=yurynorov@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3ED7E5050BE6 X-Stat-Signature: m1ha6nhpsjr4mdqi7y1fzj5px4p6xw14 X-HE-Tag: 1628975946-855568 Content-Transfer-Encoding: quoted-printable 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: bitmap_next_clear_region() calls find_next_zero_bit() and find_next_bit() sequentially to find a range of clear bits. In case of pcpu_is_populated(= ) there's a chance to return earlier if bitmap has all bits set. Signed-off-by: Yury Norov Tested-by: Wolfram Sang Acked-by: Dennis Zhou --- mm/percpu.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/mm/percpu.c b/mm/percpu.c index a43039629aa4..8bf8b88446d7 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1070,17 +1070,18 @@ static void pcpu_block_update_hint_free(struct pc= pu_chunk *chunk, int bit_off, static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int= bits, int *next_off) { - unsigned int page_start, page_end, rs, re; + unsigned int start, end; =20 - page_start =3D PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE); - page_end =3D PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE); + start =3D PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE); + end =3D PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE); =20 - rs =3D page_start; - bitmap_next_clear_region(chunk->populated, &rs, &re, page_end); - if (rs >=3D page_end) + start =3D find_next_zero_bit(chunk->populated, end, start); + if (start >=3D end) return true; =20 - *next_off =3D re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE; + end =3D find_next_bit(chunk->populated, end, start + 1); + + *next_off =3D end * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE; return false; } =20 --=20 2.30.2