diff options
| author | Eric Anholt <eric@anholt.net> | 2009-03-20 04:56:14 +0300 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2009-03-29 12:31:37 +0400 |
| commit | 955a23eb3cfc773e71b05bb7a0a0938a9e1b2568 (patch) | |
| tree | 7a9124ddf103ef1f6337484bb5e5ae51c9c288a6 | |
| parent | af7ae351ad63a137ece86740dbe3f181d09d810f (diff) | |
| download | linux-955a23eb3cfc773e71b05bb7a0a0938a9e1b2568.tar.xz | |
drm: Use a little stash on the stack to avoid kmalloc in most DRM ioctls.
The kmalloc was taking up about 1.5% of the CPU on an ioctl-heavy workload
(x11perf -aa10text on 965). Initial results look like they have a
corresponding improvement in performance for aa10text, but more numbers might
not hurt.
Thanks to ajax for pointing out this performance regression I'd introduced
back in 2007.
[airlied: well I introduced it sneakily inside Eric's patch]
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
| -rw-r--r-- | drivers/gpu/drm/drm_drv.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index c26ee0822a05..c4ada8b6295b 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -421,6 +421,7 @@ int drm_ioctl(struct inode *inode, struct file *filp, drm_ioctl_t *func; unsigned int nr = DRM_IOCTL_NR(cmd); int retcode = -EINVAL; + char stack_kdata[128]; char *kdata = NULL; atomic_inc(&dev->ioctl_count); @@ -459,10 +460,14 @@ int drm_ioctl(struct inode *inode, struct file *filp, retcode = -EACCES; } else { if (cmd & (IOC_IN | IOC_OUT)) { - kdata = kmalloc(_IOC_SIZE(cmd), GFP_KERNEL); - if (!kdata) { - retcode = -ENOMEM; - goto err_i1; + if (_IOC_SIZE(cmd) <= sizeof(stack_kdata)) { + kdata = stack_kdata; + } else { + kdata = kmalloc(_IOC_SIZE(cmd), GFP_KERNEL); + if (!kdata) { + retcode = -ENOMEM; + goto err_i1; + } } } @@ -483,7 +488,7 @@ int drm_ioctl(struct inode *inode, struct file *filp, } err_i1: - if (kdata) + if (kdata != stack_kdata) kfree(kdata); atomic_dec(&dev->ioctl_count); if (retcode) |