From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6ECFC2BD5BB for ; Tue, 22 Jul 2025 08:36:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753173370; cv=none; b=EJsUkpR/E5oZry7+F2bHsoHpKhljiKohrmcaKJ9SlQY/nsvjNvIJ7U5lrtmW4ZjMJiyLnqk7LPyeB2lJYRUqP+G0Q7ULvWU99q78vYQjSzbU3ob+F+O5eq0J99Il86QEEcXI18NWOWN7n4LTcLu377JY2yHO/HlgMdT5uk1xYtw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753173370; c=relaxed/simple; bh=n9bVkjbkbp8D4PYy1fqMbBFg8aL3F8Zum+FdA5TpMtg=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=LHF0ie0W4GeionkhGWU3qHBuq0xO7p2BPVTjWZnqCdWlsBCe6PCGlVROPQbMn5qqpVZS2QhK/J2BT4qoHefJaDpAnP0mmaW0SPVkSYYQF2ZuITdV3+u1YOdIYKCB2Z62OVjPGCVnUKfodPkRdeqcJVUFBfImP6ohHN/+YL6k1EE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IuqSx5yX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IuqSx5yX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCC31C4CEEB; Tue, 22 Jul 2025 08:36:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753173369; bh=n9bVkjbkbp8D4PYy1fqMbBFg8aL3F8Zum+FdA5TpMtg=; h=Date:Subject:To:References:From:In-Reply-To:From; b=IuqSx5yXBRB7pJ/pIi29WvPHFxCshHQ/lzWSkdekZ2IB/p/UjQuTzw1X8txQPhc87 vwv30BL28DOh3zGNnChvXU4UEH5eGYlmJ57xk52Nyp3AznJRa7bv3ONRDOEIfEFUcp /xkeyIbMXqZghbCVkCqPhhI6rJO6HzYYO3rFeeZtXucc4KnSAQoQ/wgNZMf6bjGmnW cf+1tUgjY734L0ZnoH1RBVr9UGRT2p0v+KLfeY2RxAJYNT2DSBcIicrNA3t4Cn3zOq gR1gGCPoVkyfXNwwJqDwMPHo+OHKzMT664CXH9KR6RQUmsCNfX5R16Iq/Z7CFZFTaZ 7hrmhJ7IDSsGw== Message-ID: <874a2b30-ec4d-4b72-9f25-81429f03ccb7@kernel.org> Date: Tue, 22 Jul 2025 10:36:05 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] powerpc: pci-ioda: Optimize pnv_ioda_pick_m64_pe() To: Yury Norov , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Thomas Gleixner , Frederic Barrat , Andrew Donnellan , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20250720010552.427903-1-yury.norov@gmail.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 20. 07. 25, 3:05, Yury Norov wrote: > 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 > --- > arch/powerpc/platforms/powernv/pci-ioda.c | 18 +++++------------- > 1 file changed, 5 insertions(+), 13 deletions(-) > > diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c > index d8ccf2c9b98a..c7a421ead992 100644 > --- a/arch/powerpc/platforms/powernv/pci-ioda.c > +++ b/arch/powerpc/platforms/powernv/pci-ioda.c > @@ -313,24 +313,16 @@ static struct pnv_ioda_pe *pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all) > /* Figure out reserved PE numbers by the PE */ > pnv_ioda_reserve_m64_pe(bus, pe_alloc, all); > > - /* > - * 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)) { > - kfree(pe_alloc); > - 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 = NULL; > - i = -1; > - while ((i = 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) { Makes sense. Could you also: * use bitmap_alloc() * use __cleanup() to free the bitmap * make i unsigned ? thanks, -- js suse labs