2a35703a6a
The current code uses writel()/readl(), which has an implicit memory barrier for every single readl()/writel(). Additionally, reading 4 bytes at a time over the PCI bus is not really optimal, considering that this code is running in an ioctl handler. Use memcpy_toio()/memcpy_fromio() for BAR tests. Before patch with a 4MB BAR: $ time /usr/bin/pcitest -b 1 BAR1: OKAY real 0m 1.56s After patch with a 4MB BAR: $ time /usr/bin/pcitest -b 1 BAR1: OKAY real 0m 0.54s Link: https://lore.kernel.org/linux-pci/20240322164139.678228-1-cassel@kernel.org Signed-off-by: Niklas Cassel <cassel@kernel.org> Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
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 reStructuredText 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.