> On 17/11/2023 16:12 GMT Ariel Miculas <amiculas@xxxxxxxxx> wrote: > > > When SQUASHFS_CHOICE_DECOMP_BY_MOUNT is set, the "threads" mount option > can be used to specify the decompression mode: single-threaded, > multi-threaded, percpu or the number of threads used for decompression. > When SQUASHFS_CHOICE_DECOMP_BY_MOUNT is not set, SQUASHFS_DECOMP_MULTI > and SQUASHFS_MOUNT_DECOMP_THREADS are both set, the "threads" option can > also be used to specify the number of threads used for decompression. > This mount option is only mentioned in fs/squashfs/Kconfig, which makes > it difficult to find. > > Another mount option available is "errors", which can be configured to > panic the kernel when squashfs errors are encountered. > > Add both these options to the squashfs documentation, making them more > noticeable. > > Signed-off-by: Ariel Miculas <amiculas@xxxxxxxxx> I'm happy with this. Reviewed-by: Phillip Lougher <phillip@xxxxxxxxxxxxxxx> > --- > V2 -> V3: When SQUASHFS_CHOICE_DECOMP_BY_MOUNT is not set, the "threads" > mount option also requires SQUASHFS_MOUNT_DECOMP_THREADS to be set, in > addition to SQUASHFS_DECOMP_MULTI > > V1 -> V2: When SQUASHFS_CHOICE_DECOMP_BY_MOUNT is not set, the "threads" > mount option also requires SQUASHFS_DECOMP_MULTI to be set > > Documentation/filesystems/squashfs.rst | 60 ++++++++++++++++++++++++++ > 1 file changed, 60 insertions(+) > > diff --git a/Documentation/filesystems/squashfs.rst b/Documentation/filesystems/squashfs.rst > index df42106bae71..4af8d6207509 100644 > --- a/Documentation/filesystems/squashfs.rst > +++ b/Documentation/filesystems/squashfs.rst > @@ -64,6 +64,66 @@ obtained from this site also. > The squashfs-tools development tree is now located on kernel.org > git://git.kernel.org/pub/scm/fs/squashfs/squashfs-tools.git > > +2.1 Mount options > +----------------- > +=================== ========================================================= > +errors=%s Specify whether squashfs errors trigger a kernel panic > + or not > + > + ========== ============================================= > + continue errors don't trigger a panic (default) > + panic trigger a panic when errors are encountered, > + similar to several other filesystems (e.g. > + btrfs, ext4, f2fs, GFS2, jfs, ntfs, ubifs) > + > + This allows a kernel dump to be saved, > + useful for analyzing and debugging the > + corruption. > + ========== ============================================= > +threads=%s Select the decompression mode or the number of threads > + > + If SQUASHFS_CHOICE_DECOMP_BY_MOUNT is set: > + > + ========== ============================================= > + single use single-threaded decompression (default) > + > + Only one block (data or metadata) can be > + decompressed at any one time. This limits > + CPU and memory usage to a minimum, but it > + also gives poor performance on parallel I/O > + workloads when using multiple CPU machines > + due to waiting on decompressor availability. > + multi use up to two parallel decompressors per core > + > + If you have a parallel I/O workload and your > + system has enough memory, using this option > + may improve overall I/O performance. It > + dynamically allocates decompressors on a > + demand basis. > + percpu use a maximum of one decompressor per core > + > + It uses percpu variables to ensure > + decompression is load-balanced across the > + cores. > + 1|2|3|... configure the number of threads used for > + decompression > + > + The upper limit is num_online_cpus() * 2. > + ========== ============================================= > + > + If SQUASHFS_CHOICE_DECOMP_BY_MOUNT is **not** set and > + SQUASHFS_DECOMP_MULTI, SQUASHFS_MOUNT_DECOMP_THREADS are > + both set: > + > + ========== ============================================= > + 2|3|... configure the number of threads used for > + decompression > + > + The upper limit is num_online_cpus() * 2. > + ========== ============================================= > + > +=================== ========================================================= > + > 3. Squashfs Filesystem Design > ----------------------------- > > -- > 2.42.1
