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Although scrub currently works for subpage (PAGE_SIZE > sectorsize) cases, it will allocate one page for each scrub_sector, which can cause extra unnecessary memory usage. Utilize scrub_block::pages[] instead of allocating page for each scrub_sector, this allows us to integrate larger extents while using less memory. For example, if our page size is 64K, sectorsize is 4K, and we got an 32K sized extent. We will only allocate one page for scrub_block, and all 8 scrub sectors will point to that page. To do that properly, here we introduce several small helpers: - scrub_page_get_logical() Get the logical bytenr of a page. We store the logical bytenr of the page range into page::private. But for 32bit systems, their (void *) is not large enough to contain a u64, so in that case we will need to allocate extra memory for it. For 64bit systems, we can use page::private directly. - scrub_block_get_logical() Just get the logical bytenr of the first page. - scrub_sector_get_page() Return the page which the scrub_sector points to. - scrub_sector_get_page_offset() Return the offset inside the page which the scrub_sector points to. - scrub_sector_get_kaddr() Return the address which the scrub_sector points to. Just a wrapper using scrub_sector_get_page() and scrub_sector_get_page_offset() - bio_add_scrub_sector() Please note that, even with this patch, we're still allocating one page for one sector for data extents. This is because in scrub_extent() we split the data extent using sectorsize. The memory usage reduction will need extra work to make scrub to work like data read to only use the correct sector(s). Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| 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.