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Mon, 11 Aug 2025 09:51:39 -0700 (PDT) From: Yury Norov To: "Jiri Slaby (SUSE)" , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Thomas Gleixner , Frederic Barrat , Andrew Donnellan , Yury Norov , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/2] powerpc: pci-ioda: Optimize pnv_ioda_pick_m64_pe() Date: Mon, 11 Aug 2025 12:51:28 -0400 Message-ID: <20250811165130.37552-3-yury.norov@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250811165130.37552-1-yury.norov@gmail.com> References: <20250811165130.37552-1-yury.norov@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Yury Norov (NVIDIA)" bitmap_empty() in pnv_ioda_pick_m64_pe() is O(N) and useless because the following find_next_bit() does the same work. Drop it, and while there replace a while() loop with the dedicated for_each_set_bit(). Signed-off-by: Yury Norov (NVIDIA) Reviewed-by: Andrew Donnellan --- arch/powerpc/platforms/powernv/pci-ioda.c | 19 ++++++------------- 1 file changed, 6 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platf= orms/powernv/pci-ioda.c index e2b0132fb6a1..325197ac19e5 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda.c +++ b/arch/powerpc/platforms/powernv/pci-ioda.c @@ -295,7 +295,7 @@ static struct pnv_ioda_pe *pnv_ioda_pick_m64_pe(struct = pci_bus *bus, bool all) unsigned long *pe_alloc __free(bitmap) =3D NULL; struct pnv_phb *phb =3D pci_bus_to_pnvhb(bus); struct pnv_ioda_pe *master_pe, *pe; - int i; + unsigned int i; =20 /* Root bus shouldn't use M64 */ if (pci_is_root_bus(bus)) @@ -311,23 +311,16 @@ static struct pnv_ioda_pe *pnv_ioda_pick_m64_pe(struc= t pci_bus *bus, bool all) /* Figure out reserved PE numbers by the PE */ pnv_ioda_reserve_m64_pe(bus, pe_alloc, all); =20 - /* - * the current bus might not own M64 window and that's all - * contributed by its child buses. For the case, we needn't - * pick M64 dependent PE#. - */ - if (bitmap_empty(pe_alloc, phb->ioda.total_pe_num)) { - return NULL; - } - /* * Figure out the master PE and put all slave PEs to master * PE's list to form compound PE. + * + * The current bus might not own M64 window and that's all + * contributed by its child buses. For the case, we needn't + * pick M64 dependent PE#. */ master_pe =3D NULL; - i =3D -1; - while ((i =3D find_next_bit(pe_alloc, phb->ioda.total_pe_num, i + 1)) < - phb->ioda.total_pe_num) { + for_each_set_bit(i, pe_alloc, phb->ioda.total_pe_num) { pe =3D &phb->ioda.pe_array[i]; =20 phb->ioda.m64_segmap[pe->pe_number] =3D pe->pe_number; --=20 2.43.0