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Matthew Ahrens
bbcec73783
`kmem_alloc(size>PAGESIZE, KM_SLEEP)` is backed by `kmalloc()`, which finds contiguous physical memory. If there isn't enough contiguous physical memory available (e.g. due to physical page fragmentation), the OOM killer will be invoked to make more memory available. This is not ideal because processes may be killed when there is still plenty of free memory (it just happens to be in individual pages, not contiguous runs of pages). We have observed this when allocating the ~13KB `zfs_cmd_t`, for example in `zfsdev_ioctl()`. This commit changes the behavior of `kmem_alloc(size>PAGESIZE, KM_SLEEP)` when there are insufficient contiguous free pages. In this case we will find individual pages and stitch them together using virtual memory. This is accomplished by using `kvmalloc()`, which implements the described behavior by trying `kmalloc(__GFP_NORETRY)` and falling back on `vmalloc()`. The behavior of `kmem_alloc(KM_NOSLEEP)` is not changed; it continues to use `kmalloc(GPF_ATOMIC | __GFP_NORETRY)`. This is because `vmalloc()` may sleep. Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: George Wilson <gwilson@delphix.com> Signed-off-by: Matthew Ahrens <mahrens@delphix.com> Closes #11461
OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.
Official Resources
- Documentation - for using and developing this repo
- ZoL Site - Linux release info & links
- Mailing lists
- OpenZFS site - for conference videos and info on other platforms (illumos, OSX, Windows, etc)
Installation
Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.
Contribute & Develop
We have a separate document with contribution guidelines.
We have a Code of Conduct.
Release
OpenZFS is released under a CDDL license.
For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197
Supported Kernels
- The
METAfile contains the officially recognized supported Linux kernel versions. - Supported FreeBSD versions are any supported branches and releases starting from 12.2-RELEASE.