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Bottomley" , Helge Deller , Michael Ellerman , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Chris Zankel , Max Filippov , Madhavan Srinivasan , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , linux-kernel@vger.kernel.org, Xifer Subject: Re: [PATCH 00/10] PCI: Improve head free space usage Message-ID: <20260326192520.GA1337681@bhelgaas> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260324165633.4583-1-ilpo.jarvinen@linux.intel.com> [+cc Xifer; thanks very much for reporting and testing!] On Tue, Mar 24, 2026 at 06:56:23PM +0200, Ilpo Järvinen wrote: > Hi all, > > This series attempts to take advantage of free head space (the free > space before the aligned start address) in order to generally produce a > tighter packing of the resources/bridge windows. > > The recent changes to the resource fitting algorithm caused resource > allocation failures in some cases where a bridge window that is sized > to be gapless could no longer be assigned. The previous algorithm left > a huge gaps which allowed it to place the remainder (non-aligning part > of the size) before the start address of used for the gapless fit, > whereas the new gapless approach always had to place the remainder > after the aligning part of the resources. There is not always space > for the remainder triggering those failures (e.g., when the aligning > part must be placed at the top of the window). > > This series attempts to allow placing the remainder once again before > the aligning part, but now without leaving huge gaps to retain the > benefits of the gapless bridge windows. The approach is somewhat hacky > but should work thanks to PCI resources fundamentally consisting only > power-of-two atoms. > > There maybe cases where architecture would not want to do such > relocation. This series adds the relocation to arch > pcibios_align_resource() functions to allow all of them taking > advantage of the better resource packing but if somebody objects doing > this relocation for a particular arch, I can remove it, please just let > me know (this relocation doesn't seem critical unless there are > regressions). > > Ilpo Järvinen (10): > resource: Add __resource_contains_unbound() for internal contains > checks > resource: Pass full extent of empty space to resource_alignf CB > resource: Rename 'tmp' variable to 'full_avail' > ARM/PCI: Remove unnecessary second application of align > am68k/PCI: Remove unnecessary second application of align > MIPS: PCI: Remove unnecessary second application of align > parisc/PCI: Cleanup align handling > PCI: Rename window_alignment() to pci_min_window_alignment() > PCI: Align head space better > PCI: Fix alignment calculation for resource size larger than align > > arch/alpha/kernel/pci.c | 1 + > arch/arm/kernel/bios32.c | 9 ++++--- > arch/m68k/kernel/pcibios.c | 8 +++++-- > arch/mips/pci/pci-generic.c | 8 ++++--- > arch/mips/pci/pci-legacy.c | 3 +++ > arch/parisc/kernel/pci.c | 17 ++++++++------ > arch/powerpc/kernel/pci-common.c | 6 ++++- > arch/s390/pci/pci.c | 1 + > arch/sh/drivers/pci/pci.c | 6 ++++- > arch/x86/pci/i386.c | 5 +++- > arch/xtensa/kernel/pci.c | 3 +++ > drivers/pci/pci.h | 3 +++ > drivers/pci/setup-bus.c | 15 ++++++++---- > drivers/pci/setup-res.c | 40 +++++++++++++++++++++++++++++++- > drivers/pcmcia/rsrc_nonstatic.c | 3 ++- > include/linux/ioport.h | 22 +++++++++++++++--- > include/linux/pci.h | 12 +++++++--- > kernel/resource.c | 33 +++++++++++++------------- > 18 files changed, 149 insertions(+), 46 deletions(-) I added Xifer's tested-by, fixed the "am68k" and missing "if" typos, and applied these to pci/resource for v7.1. Ilpo, if you post a v2 with more changes, I'll update to it. I applied the series now to get a head start on 0-day building and into next.