| Message ID | 20250212154358.2540389-1-grygorii_strashko@epam.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | device-tree: optimize size of struct dt_device_node | expand |
On Wed, 12 Feb 2025, Grygorii Strashko wrote: > From: Michal Orzel <michal.orzel@amd.com> > > The current placement of fields in struct dt_device_node is not optimal and > introduces holes due to fields alignment. > > Checked with "'pahole xen-syms -C dt_device_node" > > ARM64 size 144B, 16B holes: > /* size: 144, cachelines: 3, members: 15 */ > /* sum members: 128, holes: 3, sum holes: 16 */ > /* last cacheline: 16 bytes */ > ARM32 size 72B, 4B holes > /* size: 72, cachelines: 2, members: 15 */ > /* sum members: 68, holes: 2, sum holes: 4 */ > /* last cacheline: 8 bytes */ > > This patch optimizes size of struct dt_device_node by rearranging its > field, which eliminates holes and reduces structure size by 16B(ARM64) and > 4B(ARM32). > > After ARM64 size 128B, no holes (-16B): > /* size: 128, cachelines: 2, members: 15 */ > After ARM32 size 68B, no holes (-4B) > /* size: 68, cachelines: 2, members: 15 */ > /* last cacheline: 4 bytes */ > > Signed-off-by: Michal Orzel <michal.orzel@amd.com> > Signed-off-by: Grygorii Strashko <grygorii_strashko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> > --- > This patch follows discussion in [1] > [1] https://patchwork.kernel.org/comment/26239672/ > > xen/include/xen/device_tree.h | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h > index 5ff763bb80bb..0ff80fda04da 100644 > --- a/xen/include/xen/device_tree.h > +++ b/xen/include/xen/device_tree.h > @@ -81,17 +81,10 @@ struct dt_property { > struct dt_device_node { > const char *name; > const char *type; > - dt_phandle phandle; > char *full_name; > + dt_phandle phandle; > domid_t used_by; /* By default it's used by dom0 */ > > - struct dt_property *properties; > - struct dt_device_node *parent; > - struct dt_device_node *child; > - struct dt_device_node *sibling; > - struct dt_device_node *next; /* TODO: Remove it. Only use to know the last children */ > - struct dt_device_node *allnext; > - > /* IOMMU specific fields */ > bool is_protected; > > @@ -100,6 +93,13 @@ struct dt_device_node { > bool static_evtchn_created; > #endif > > + struct dt_property *properties; > + struct dt_device_node *parent; > + struct dt_device_node *child; > + struct dt_device_node *sibling; > + struct dt_device_node *next; /* TODO: Remove it. Only use to know the last children */ > + struct dt_device_node *allnext; > + > /* > * The main purpose of this list is to link the structure in the list > * of devices assigned to domain. > -- > 2.34.1 >
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h index 5ff763bb80bb..0ff80fda04da 100644 --- a/xen/include/xen/device_tree.h +++ b/xen/include/xen/device_tree.h @@ -81,17 +81,10 @@ struct dt_property { struct dt_device_node { const char *name; const char *type; - dt_phandle phandle; char *full_name; + dt_phandle phandle; domid_t used_by; /* By default it's used by dom0 */ - struct dt_property *properties; - struct dt_device_node *parent; - struct dt_device_node *child; - struct dt_device_node *sibling; - struct dt_device_node *next; /* TODO: Remove it. Only use to know the last children */ - struct dt_device_node *allnext; - /* IOMMU specific fields */ bool is_protected; @@ -100,6 +93,13 @@ struct dt_device_node { bool static_evtchn_created; #endif + struct dt_property *properties; + struct dt_device_node *parent; + struct dt_device_node *child; + struct dt_device_node *sibling; + struct dt_device_node *next; /* TODO: Remove it. Only use to know the last children */ + struct dt_device_node *allnext; + /* * The main purpose of this list is to link the structure in the list * of devices assigned to domain.