2e16929660
Currently it calls pagevec_lookup_range_nr_tag(), but that may be inefficient, as we might end up having to search several times as we get down to looking for fewer pages to fill the array. Thus spake Willy: "I think ceph is misusing pagevec_lookup_range_nr_tag(). Let's suppose you get a range which is AAAAbbbbAAAAbbbbAAAAbbbbbbbb(...)bbbbAAAA and you try to fetch max_pages=13. First loop will get AAAAbbbbAAAAb and have 8 locked_pages. The next call will get bbbAA and now locked_pages=10. Next call gets AAb ... and now you're iterating your way through all the 'b' one page at a time until you find that first A." 'A' here refers to pages that are eligible for writeback and 'b' represents ones that aren't (for whatever reason). Not capping the number of return pages may mean that we sometimes find more pages than are needed, but the extra references will just get put at the end. Ceph is also the only caller of pagevec_lookup_range_nr_tag(), so this change should allow us to eliminate that call as well. That will be done in a follow-on patch. Reported-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.