4900be8360
Devices with many queues allocate a huge number of interrupts and get assigned a vector for each of them, even if the queues are not active and the interrupts never requested. This causes problems with the decision whether the global vector space is sufficient for CPU hot unplug operations. Change it to a reservation scheme, which allows overcommitment. When the interrupt is allocated and initialized the vector assignment merily updates the reservation request counter in the matrix allocator. This counter is used to emit warnings when the reservation exceeds the available vector space, but does not affect CPU offline operations. Like the managed interrupts the corresponding MSI/DMAR/IOAPIC entries are directed to the special shutdown vector. When the interrupt is requested, then the activation code tries to assign a real vector. If that succeeds the interrupt is started up and functional. If that fails, then subsequently request_irq() fails with -ENOSPC. This allows a clear separation of inactive and active modes and simplifies the final decisions whether the global vector space is sufficient for CPU offline operations. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Yu Chen <yu.c.chen@intel.com> Acked-by: Juergen Gross <jgross@suse.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Alok Kataria <akataria@vmware.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Rui Zhang <rui.zhang@intel.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Len Brown <lenb@kernel.org> Link: https://lkml.kernel.org/r/20170913213156.184211133@linutronix.de |
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.