On Thu, Jun 24, 2021 at 03:49:55PM +0200, Michal Wajdeczko wrote: > > > On 24.06.2021 09:04, Matthew Brost wrote: > > With the introduction of non-blocking CTBs more than one CTB can be in > > flight at a time. Increasing the size of the CTBs should reduce how > > often software hits the case where no space is available in the CTB > > buffer. > > > > Cc: John Harrison <john.c.harrison@xxxxxxxxx> > > Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx> > > --- > > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 11 ++++++++--- > > 1 file changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > > index 07f080ddb9ae..a17215920e58 100644 > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c > > @@ -58,11 +58,16 @@ static inline struct drm_device *ct_to_drm(struct intel_guc_ct *ct) > > * +--------+-----------------------------------------------+------+ > > * > > * Size of each `CT Buffer`_ must be multiple of 4K. > > - * As we don't expect too many messages, for now use minimum sizes. > > + * We don't expect too many messages in flight at any time, unless we are > > + * using the GuC submission. In that case each request requires a minimum > > + * 2 dwords which gives us a maximum 256 queue'd requests. Hopefully this > > + * enough space to avoid backpressure on the driver. We increase the size > > + * of the receive buffer (relative to the send) to ensure a G2H response > > + * CTB has a landing spot. > > */ > > #define CTB_DESC_SIZE ALIGN(sizeof(struct guc_ct_buffer_desc), SZ_2K) > > #define CTB_H2G_BUFFER_SIZE (SZ_4K) > > -#define CTB_G2H_BUFFER_SIZE (SZ_4K) > > +#define CTB_G2H_BUFFER_SIZE (4 * CTB_H2G_BUFFER_SIZE) > > > > struct ct_request { > > struct list_head link; > > @@ -641,7 +646,7 @@ static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg) > > /* beware of buffer wrap case */ > > if (unlikely(available < 0)) > > available += size; > > - CT_DEBUG(ct, "available %d (%u:%u)\n", available, head, tail); > > + CT_DEBUG(ct, "available %d (%u:%u:%u)\n", available, head, tail, size); > > CTB size is already printed in intel_guc_ct_init() and is fixed so not > sure if repeating it on every ct_read has any benefit > I'd say more debug the better and if CT_DEBUG is enabled the logs are very verbose so an extra value doesn't really hurt. Matt > > GEM_BUG_ON(available < 0); > > > > header = cmds[head]; > >