Update ABD stats for linear page Linux

a10e552 updated abd_free_linear_page() to no longer call abd_update_scatter_stat(). This meant that linear pages that were not attached to Direct I/O requests were not doing waste accounting for the ARC. This led to performance issues due to incorrect ARC accounting that resulted in 100% of CPU time being spent in arc_evict() during prolonged I/O workloads with the ARC. The call to abd_update_scatter_stats() is now conditionally called in abd_free_linear_page() when the ABD is not from a Direct I/O request. Reviewed-by: Mark Maybee <[email protected]> Reviewed-by: Tony Nguyen <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Alexander Motin <[email protected]> Signed-off-by: Brian Atkinson <[email protected]> Closes #16729
openzfs · Nov 7, 2024 · 187f931 · 187f931
1 parent 5945676
commit 187f931
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/module/os/linux/zfs/abd_os.c b/module/os/linux/zfs/abd_os.c
@@ -701,6 +701,8 @@ abd_free_linear_page(abd_t *abd)
 	/* When backed by user page unmap it */
 	if (abd_is_from_pages(abd))
 		zfs_kunmap(sg_page(sg));
+	else
+		abd_update_scatter_stats(abd, ABDSTAT_DECR);
 
 	abd->abd_flags &= ~ABD_FLAG_LINEAR;
 	abd->abd_flags &= ~ABD_FLAG_LINEAR_PAGE;