[OpenWrt-Devel] [PATCH v2] kernel: ath10k-ct: provide a build variant for small RAM devices

Paul Fertser fercerpav at gmail.com
Sun Dec 15 12:25:22 EST 2019 

According to many bugreports [0][1][2] the default ath10k-ct kernel
module is unusable on devices with just 64 MiB RAM or with 128 MiB and
dual ath10k cards. The target boards boot but eventually oom-killer
starts to interfere with normal operation, so the current state is
effectively broken.

Since the two patches in question have a performance impact (and
possibly some other unexpected side-effects) a dedicated build variant
is added so that users of the low RAM devices can still benefit from all
the ath10k-ct advantages.

According to testing [3] results, the issue can be experienced even with
"a 256MB device with three radios". Measured performance impact of
implementing small buffers was lowering "the maximum 5 GHz throughput on
an IPQ40xx device without RPS/XPS optimizations from 494/432 Mbit/s for
TCP transfers (download/upload) to 438/343 Mbit/s"

The patches were apparently inspired by QSDK tweaks used by ODMs for the
affected devices.

[0] http://lists.infradead.org/pipermail/openwrt-devel/2019-December/020573.html
[1] https://github.com/openwrt/openwrt/pull/1077
[2] https://bugs.openwrt.org/index.php?do=details&task_id=2664
[3] https://github.com/freifunk-gluon/gluon/pull/1440#issue-195607701

Signed-off-by: Paul Fertser <fercerpav at gmail.com>
---
Changes for v2:

    - Added performance impact details to the commit message
    - Fixed QUILT=1 operation
    - Refreshed the new patches

 package/kernel/ath10k-ct/Makefile             | 30 +++++++-
 ...0-0010-ath10k-limit-htt-rx-ring-size.patch | 22 ++++++
 ...60-0011-ath10k-limit-pci-buffer-size.patch | 76 +++++++++++++++++++
 3 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 package/kernel/ath10k-ct/patches-smallbuffers/960-0010-ath10k-limit-htt-rx-ring-size.patch
 create mode 100644 package/kernel/ath10k-ct/patches-smallbuffers/960-0011-ath10k-limit-pci-buffer-size.patch

diff --git a/package/kernel/ath10k-ct/Makefile b/package/kernel/ath10k-ct/Makefile
index dbf75fe174..99ec225570 100644
--- a/package/kernel/ath10k-ct/Makefile
+++ b/package/kernel/ath10k-ct/Makefile
@@ -35,6 +35,7 @@ define KernelPackage/ath10k-ct
 	$(PKG_BUILD_DIR)/ath10k$(CT_KVER)/ath10k_core.ko
   AUTOLOAD:=$(call AutoProbe,ath10k_pci)
   PROVIDES:=kmod-ath10k
+  VARIANT:=regular
 endef
 
 define KernelPackage/ath10k-ct/config
@@ -42,7 +43,17 @@ define KernelPackage/ath10k-ct/config
        config ATH10K-CT_LEDS
                bool "Enable LED support"
                default y
-               depends on PACKAGE_kmod-ath10k-ct
+               depends on PACKAGE_kmod-ath10k-ct || PACKAGE_kmod-ath10k-ct-smallbuffers
+endef
+
+define KernelPackage/ath10k-ct-smallbuffers
+$(call KernelPackage/ath10k-ct)
+  TITLE+= (small buffers for low-RAM devices)
+  VARIANT:=smallbuffers
+endef
+
+define KernelPackage/ath10k-ct-smallbuffers/config
+$(call KernelPackage/ath10k-ct/config)
 endef
 
 NOSTDINC_FLAGS = \
@@ -90,6 +101,22 @@ ifeq ($(CONFIG_ATH10K-CT_LEDS),y)
   NOSTDINC_FLAGS += -DCONFIG_ATH10K_LEDS
 endif
 
+define Build/Patch
+	$(if $(QUILT),rm -rf $(PKG_BUILD_DIR)/patches; mkdir -p $(PKG_BUILD_DIR)/patches)
+	$(call PatchDir,$(PKG_BUILD_DIR),$(PATCH_DIR),regular/)
+ifeq ($(BUILD_VARIANT),smallbuffers)
+	$(call PatchDir,$(PKG_BUILD_DIR),$(PATCH_DIR)-$(BUILD_VARIANT),$(BUILD_VARIANT)/)
+endif
+	$(if $(QUILT),touch $(PKG_BUILD_DIR)/.quilt_used)
+endef
+
+define Quilt/Refresh/Package
+	$(call Quilt/RefreshDir,$(PKG_BUILD_DIR),$(PATCH_DIR),regular/)
+ifeq ($(BUILD_VARIANT),smallbuffers)
+	$(call Quilt/RefreshDir,$(PKG_BUILD_DIR),$(PATCH_DIR)-$(BUILD_VARIANT),$(BUILD_VARIANT)/)
+endif
+endef
+
 define Build/Configure
 	cp $(STAGING_DIR)/usr/include/mac80211/ath/*.h $(PKG_BUILD_DIR)
 endef
@@ -107,3 +134,4 @@ define Build/Compile
 endef
 
 $(eval $(call KernelPackage,ath10k-ct))
+$(eval $(call KernelPackage,ath10k-ct-smallbuffers))
diff --git a/package/kernel/ath10k-ct/patches-smallbuffers/960-0010-ath10k-limit-htt-rx-ring-size.patch b/package/kernel/ath10k-ct/patches-smallbuffers/960-0010-ath10k-limit-htt-rx-ring-size.patch
new file mode 100644
index 0000000000..fcc5927759
--- /dev/null
+++ b/package/kernel/ath10k-ct/patches-smallbuffers/960-0010-ath10k-limit-htt-rx-ring-size.patch
@@ -0,0 +1,22 @@
+--- a/ath10k-4.19/htt.h
++++ b/ath10k-4.19/htt.h
+@@ -237,7 +237,7 @@ enum htt_rx_ring_flags {
+ };
+ 
+ #define HTT_RX_RING_SIZE_MIN 128
+-#define HTT_RX_RING_SIZE_MAX 2048
++#define HTT_RX_RING_SIZE_MAX 512
+ #define HTT_RX_RING_SIZE HTT_RX_RING_SIZE_MAX
+ #define HTT_RX_RING_FILL_LEVEL (((HTT_RX_RING_SIZE) / 2) - 1)
+ #define HTT_RX_RING_FILL_LEVEL_DUAL_MAC (HTT_RX_RING_SIZE - 1)
+--- a/ath10k-5.2/htt.h
++++ b/ath10k-5.2/htt.h
+@@ -225,7 +225,7 @@ enum htt_rx_ring_flags {
+ };
+ 
+ #define HTT_RX_RING_SIZE_MIN 128
+-#define HTT_RX_RING_SIZE_MAX 2048
++#define HTT_RX_RING_SIZE_MAX 512
+ #define HTT_RX_RING_SIZE HTT_RX_RING_SIZE_MAX
+ #define HTT_RX_RING_FILL_LEVEL (((HTT_RX_RING_SIZE) / 2) - 1)
+ #define HTT_RX_RING_FILL_LEVEL_DUAL_MAC (HTT_RX_RING_SIZE - 1)
diff --git a/package/kernel/ath10k-ct/patches-smallbuffers/960-0011-ath10k-limit-pci-buffer-size.patch b/package/kernel/ath10k-ct/patches-smallbuffers/960-0011-ath10k-limit-pci-buffer-size.patch
new file mode 100644
index 0000000000..c54b36731e
--- /dev/null
+++ b/package/kernel/ath10k-ct/patches-smallbuffers/960-0011-ath10k-limit-pci-buffer-size.patch
@@ -0,0 +1,76 @@
+--- a/ath10k-4.19/pci.c
++++ b/ath10k-4.19/pci.c
+@@ -142,7 +142,7 @@ static struct ce_attr host_ce_config_wla
+ 		.flags = CE_ATTR_FLAGS,
+ 		.src_nentries = 0,
+ 		.src_sz_max = 2048,
+-		.dest_nentries = 512,
++		.dest_nentries = 128,
+ 		.recv_cb = ath10k_pci_htt_htc_rx_cb,
+ 	},
+ 
+@@ -151,7 +151,7 @@ static struct ce_attr host_ce_config_wla
+ 		.flags = CE_ATTR_FLAGS,
+ 		.src_nentries = 0,
+ 		.src_sz_max = 2048,
+-		.dest_nentries = 128,
++		.dest_nentries = 64,
+ 		.recv_cb = ath10k_pci_htc_rx_cb,
+ 	},
+ 
+@@ -178,7 +178,7 @@ static struct ce_attr host_ce_config_wla
+ 		.flags = CE_ATTR_FLAGS,
+ 		.src_nentries = 0,
+ 		.src_sz_max = 512,
+-		.dest_nentries = 512,
++		.dest_nentries = 128,
+ 		.recv_cb = ath10k_pci_htt_rx_cb,
+ 	},
+ 
+@@ -203,7 +203,7 @@ static struct ce_attr host_ce_config_wla
+ 		.flags = CE_ATTR_FLAGS,
+ 		.src_nentries = 0,
+ 		.src_sz_max = 2048,
+-		.dest_nentries = 128,
++		.dest_nentries = 96,
+ 		.recv_cb = ath10k_pci_pktlog_rx_cb,
+ 	},
+ 
+--- a/ath10k-5.2/pci.c
++++ b/ath10k-5.2/pci.c
+@@ -131,7 +131,7 @@ static struct ce_attr host_ce_config_wla
+ 		.flags = CE_ATTR_FLAGS,
+ 		.src_nentries = 0,
+ 		.src_sz_max = 2048,
+-		.dest_nentries = 512,
++		.dest_nentries = 128,
+ 		.recv_cb = ath10k_pci_htt_htc_rx_cb,
+ 	},
+ 
+@@ -140,7 +140,7 @@ static struct ce_attr host_ce_config_wla
+ 		.flags = CE_ATTR_FLAGS,
+ 		.src_nentries = 0,
+ 		.src_sz_max = 2048,
+-		.dest_nentries = 128,
++		.dest_nentries = 64,
+ 		.recv_cb = ath10k_pci_htc_rx_cb,
+ 	},
+ 
+@@ -167,7 +167,7 @@ static struct ce_attr host_ce_config_wla
+ 		.flags = CE_ATTR_FLAGS,
+ 		.src_nentries = 0,
+ 		.src_sz_max = 512,
+-		.dest_nentries = 512,
++		.dest_nentries = 128,
+ 		.recv_cb = ath10k_pci_htt_rx_cb,
+ 	},
+ 
+@@ -192,7 +192,7 @@ static struct ce_attr host_ce_config_wla
+ 		.flags = CE_ATTR_FLAGS,
+ 		.src_nentries = 0,
+ 		.src_sz_max = 2048,
+-		.dest_nentries = 128,
++		.dest_nentries = 96,
+ 		.recv_cb = ath10k_pci_pktlog_rx_cb,
+ 	},
+ 
-- 
2.20.1


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