c/mirror_zfs
1
0
Fork 0
mirror of https://git.proxmox.com/git/mirror_zfs.git synced 2026-05-24 11:18:52 +03:00
Code Issues Packages Projects Releases Wiki Activity

Wire O_DIRECT also to Uncached I/O (#17218)

Browse Source 
Before Direct I/O was implemented, I've implemented lighter version
I called Uncached I/O.  It uses normal DMU/ARC data path with some
optimizations, but evicts data from caches as soon as possible and
reasonable.  Originally I wired it only to a primarycache property,
but now completing the integration all the way up to the VFS.

While Direct I/O has the lowest possible memory bandwidth usage,
it also has a significant number of limitations.  It require I/Os
to be page aligned, does not allow speculative prefetch, etc.  The
Uncached I/O does not have those limitations, but instead require
additional memory copy, though still one less than regular cached
I/O.  As such it should fill the gap in between.  Considering this
I've disabled annoying EINVAL errors on misaligned requests, adding
a tunable for those who wants to test their applications.

To pass the information between the layers I had to change a number
of APIs.  But as side effect upper layers can now control not only
the caching, but also speculative prefetch.  I haven't wired it to
VFS yet, since it require looking on some OS specifics.  But while
there I've implemented speculative prefetch of indirect blocks for
Direct I/O, controllable via all the same mechanisms.

Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Fixes #17027
Reviewed-by: Rob Norris <robn@despairlabs.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Alexander Motin
2025-05-13 17:26:55 -04:00
committed by GitHub
parent e2ba0f7643
commit 734eba251d
35 changed files with 397 additions and 294 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/zvol.c
+4 -3
View File
@@ -900,8 +900,9 @@ zvol_log_write(zvol_state_t *zv, dmu_tx_t *tx, uint64_t offset,
itx = zil_itx_create(TX_WRITE, sizeof (*lr) +
(wr_state == WR_COPIED ? len : 0));
lr = (lr_write_t *)&itx->itx_lr;
if (wr_state == WR_COPIED && dmu_read_by_dnode(zv->zv_dn,
offset, len, lr+1, DMU_READ_NO_PREFETCH) != 0) {
if (wr_state == WR_COPIED &&
dmu_read_by_dnode(zv->zv_dn, offset, len, lr + 1,
DMU_READ_NO_PREFETCH | DMU_KEEP_CACHING) != 0) {
zil_itx_destroy(itx);
itx = zil_itx_create(TX_WRITE, sizeof (*lr));
lr = (lr_write_t *)&itx->itx_lr;
@@ -994,7 +995,7 @@ zvol_get_data(void *arg, uint64_t arg2, lr_write_t *lr, char *buf,
zgd->zgd_lr = zfs_rangelock_enter(&zv->zv_rangelock, offset,
size, RL_READER);
error = dmu_read_by_dnode(zv->zv_dn, offset, size, buf,
DMU_READ_NO_PREFETCH);
DMU_READ_NO_PREFETCH | DMU_KEEP_CACHING);
} else { /* indirect write */
ASSERT3P(zio, !=, NULL);
/*