mainlining shenanigans
612b72862b
The NVME PCI driver contains a tedious mechanism for interrupt allocation, which is necessary to adjust the number and size of interrupt sets to the maximum available number of interrupts which depends on the underlying PCI capabilities and the available CPU resources. It works around the former short comings of the PCI and core interrupt allocation mechanims in combination with interrupt sets. The PCI interrupt allocation function allows to provide a maximum and a minimum number of interrupts to be allocated and tries to allocate as many as possible. This worked without driver interaction as long as there was only a single set of interrupts to handle. With the addition of support for multiple interrupt sets in the generic affinity spreading logic, which is invoked from the PCI interrupt allocation, the adaptive loop in the PCI interrupt allocation did not work for multiple interrupt sets. The reason is that depending on the total number of interrupts which the PCI allocation adaptive loop tries to allocate in each step, the number and the size of the interrupt sets need to be adapted as well. Due to the way the interrupt sets support was implemented there was no way for the PCI interrupt allocation code or the core affinity spreading mechanism to invoke a driver specific function for adapting the interrupt sets configuration. As a consequence the driver had to implement another adaptive loop around the PCI interrupt allocation function and calling that with maximum and minimum interrupts set to the same value. This ensured that the allocation either succeeded or immediately failed without any attempt to adjust the number of interrupts in the PCI code. The core code now allows drivers to provide a callback to recalculate the number and the size of interrupt sets during PCI interrupt allocation, which in turn allows the PCI interrupt allocation function to be called in the same way as with a single set of interrupts. The PCI code handles the adaptive loop and the interrupt affinity spreading mechanism invokes the driver callback to adapt the interrupt set configuration to the current loop value. This replaces the adaptive loop in the driver completely. Implement the NVME specific callback which adjusts the interrupt sets configuration and remove the adaptive allocation loop. [ tglx: Simplify the callback further and restore the dropped adjustment of number of sets ] Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Bjorn Helgaas <helgaas@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org Cc: Sagi Grimberg <sagi@grimberg.me> Cc: linux-nvme@lists.infradead.org Cc: linux-pci@vger.kernel.org Cc: Keith Busch <keith.busch@intel.com> Cc: Sumit Saxena <sumit.saxena@broadcom.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Shivasharan Srikanteshwara <shivasharan.srikanteshwara@broadcom.com> Link: https://lkml.kernel.org/r/20190216172228.602546658@linutronix.de |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.