| Message ID | 20220311103527.12931-1-jgross@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xen/blkfront: speed up purge_persistent_grants() | expand |
On 11.03.2022 11:35, Juergen Gross wrote: > purge_persistent_grants() is scanning the grants list for persistent > grants being no longer in use by the backend. When having found such a > grant, it will be set to "invalid" and pushed to the tail of the list. > > Instead of pushing it directly to the end of the list, add it first to > a temporary list, avoiding to scan those entries again in the main > list traversal. After having finished the scan, append the temporary > list to the grant list. > > Suggested-by: Jan Beulich <jbeulich@suse.com> > Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com>
On Fri, Mar 11, 2022 at 11:35:27AM +0100, Juergen Gross wrote: > purge_persistent_grants() is scanning the grants list for persistent > grants being no longer in use by the backend. When having found such a > grant, it will be set to "invalid" and pushed to the tail of the list. > > Instead of pushing it directly to the end of the list, add it first to > a temporary list, avoiding to scan those entries again in the main > list traversal. After having finished the scan, append the temporary > list to the grant list. > > Suggested-by: Jan Beulich <jbeulich@suse.com> > Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com> Thanks.
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index aa996b637d0b..378262ec47ae 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -2533,6 +2533,7 @@ static void purge_persistent_grants(struct blkfront_info *info) for_each_rinfo(info, rinfo, i) { struct grant *gnt_list_entry, *tmp; + LIST_HEAD(grants); spin_lock_irqsave(&rinfo->ring_lock, flags); @@ -2550,9 +2551,11 @@ static void purge_persistent_grants(struct blkfront_info *info) list_del(&gnt_list_entry->node); rinfo->persistent_gnts_c--; gnt_list_entry->gref = GRANT_INVALID_REF; - list_add_tail(&gnt_list_entry->node, &rinfo->grants); + list_add_tail(&gnt_list_entry->node, &grants); } + list_splice_tail(&grants, &rinfo->grants); + spin_unlock_irqrestore(&rinfo->ring_lock, flags); } }
purge_persistent_grants() is scanning the grants list for persistent grants being no longer in use by the backend. When having found such a grant, it will be set to "invalid" and pushed to the tail of the list. Instead of pushing it directly to the end of the list, add it first to a temporary list, avoiding to scan those entries again in the main list traversal. After having finished the scan, append the temporary list to the grant list. Suggested-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com> --- drivers/block/xen-blkfront.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)