[Qemu-devel] [PATCH 01/11] slavio_timer: avoid structure holes spotted by pahole

[Blue Swirl]

Report from pahole on amd64 host:
struct SLAVIO_TIMERState {
        SysBusDevice               busdev;               /*     0  5648 */
        /* --- cacheline 88 boundary (5632 bytes) was 16 bytes ago --- */
        uint32_t                   num_cpus;             /*  5648     4 */

        /* XXX 4 bytes hole, try to pack */

        CPUTimerState              cputimer[17];         /*  5656   816 */
        /* --- cacheline 101 boundary (6464 bytes) was 8 bytes ago --- */
        uint32_t                   cputimer_mode;        /*  6472     4 */

        /* size: 6480, cachelines: 102 */
        /* sum members: 6472, holes: 1, sum holes: 4 */
        /* padding: 4 */
        /* last cacheline: 16 bytes */
};      /* definitions: 1 */

struct CPUTimerState {
        qemu_irq                   irq;                  /*     0     8 */
        ptimer_state *             timer;                /*     8     8 */
        uint32_t                   count;                /*    16     4 */
        uint32_t                   counthigh;            /*    20     4 */
        uint32_t                   reached;              /*    24     4 */

        /* XXX 4 bytes hole, try to pack */

        uint64_t                   limit;                /*    32     8 */
        uint32_t                   running;              /*    40     4 */

        /* size: 48, cachelines: 1 */
        /* sum members: 40, holes: 1, sum holes: 4 */
        /* padding: 4 */
        /* last cacheline: 48 bytes */
};      /* definitions: 1 */

Fix by rearranging the structures to avoid padding.

Signed-off-by: Blue Swirl <address@hidden>
---
 hw/slavio_timer.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/slavio_timer.c b/hw/slavio_timer.c
index 5511313..f18c8d7 100644
--- a/hw/slavio_timer.c
+++ b/hw/slavio_timer.c
@@ -48,16 +48,16 @@ typedef struct CPUTimerState {
     qemu_irq irq;
     ptimer_state *timer;
     uint32_t count, counthigh, reached;
-    uint64_t limit;
-    // processor only
+    /* processor only */
     uint32_t running;
+    uint64_t limit;
 } CPUTimerState;

 typedef struct SLAVIO_TIMERState {
     SysBusDevice busdev;
     uint32_t num_cpus;
-    CPUTimerState cputimer[MAX_CPUS + 1];
     uint32_t cputimer_mode;
+    CPUTimerState cputimer[MAX_CPUS + 1];
 } SLAVIO_TIMERState;

 typedef struct TimerContext {
-- 
1.6.2.4

0001-slavio_timer-avoid-structure-holes-spotted-by-pahole.patch
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