diff --git a/infra/bots/recipes/perf.expected/Perf-Android-Clang-PixelC-GPU-TegraX1-arm64-Release-Android.json b/infra/bots/recipes/perf.expected/Perf-Android-Clang-PixelC-GPU-TegraX1-arm64-Release-Android.json
index f362a87..567ef26 100644
--- a/infra/bots/recipes/perf.expected/Perf-Android-Clang-PixelC-GPU-TegraX1-arm64-Release-Android.json
+++ b/infra/bots/recipes/perf.expected/Perf-Android-Clang-PixelC-GPU-TegraX1-arm64-Release-Android.json
@@ -597,7 +597,7 @@
       "--json-output",
       "/path/to/tmp/json",
       "copy",
-      "set -x; /data/local/tmp/nanobench -i /sdcard/revenge_of_the_skiabot/resources --skps /sdcard/revenge_of_the_skiabot/skps --images /sdcard/revenge_of_the_skiabot/images/nanobench --svgs /sdcard/revenge_of_the_skiabot/svgs --pre_log --images --gpuStatsDump true --useThermalManager 1,1,10,1000 --scales 1.0 1.1 --nocpu --config gles glessrgb glesmsaa4 glesnvpr4 glesnvprdit4 glesinst glesinst4 --match ~blurroundrect ~patch_grid ~desk_carsvg ~inc0.gif ~inc1.gif ~incInterlaced.gif ~inc0.jpg ~incGray.jpg ~inc0.wbmp ~inc1.wbmp ~inc0.webp ~inc1.webp ~inc0.ico ~inc1.ico ~inc0.png ~inc1.png ~inc2.png ~inc12.png ~inc13.png ~inc14.png ~inc0.webp ~inc1.webp --outResultsFile /sdcard/revenge_of_the_skiabot/perf/nanobench_abc123_1337000001.json --properties gitHash abc123 swarming_bot_id skia-bot-123 swarming_task_id 123456 --key arch arm64 compiler Clang cpu_or_gpu GPU cpu_or_gpu_value TegraX1 extra_config Android model PixelC os Android; echo $? >/data/local/tmp/rc",
+      "set -x; /data/local/tmp/nanobench -i /sdcard/revenge_of_the_skiabot/resources --skps /sdcard/revenge_of_the_skiabot/skps --images /sdcard/revenge_of_the_skiabot/images/nanobench --svgs /sdcard/revenge_of_the_skiabot/svgs --pre_log --images --gpuStatsDump true --useThermalManager 1,1,10,1000 --scales 1.0 1.1 --nocpu --config gles glessrgb glesmsaa4 glesnvpr4 glesnvprdit4 glesinst glesinst4 --gpuThreads 0 --match ~blurroundrect ~patch_grid ~desk_carsvg ~inc0.gif ~inc1.gif ~incInterlaced.gif ~inc0.jpg ~incGray.jpg ~inc0.wbmp ~inc1.wbmp ~inc0.webp ~inc1.webp ~inc0.ico ~inc1.ico ~inc0.png ~inc1.png ~inc2.png ~inc12.png ~inc13.png ~inc14.png ~inc0.webp ~inc1.webp --outResultsFile /sdcard/revenge_of_the_skiabot/perf/nanobench_abc123_1337000001.json --properties gitHash abc123 swarming_bot_id skia-bot-123 swarming_task_id 123456 --key arch arm64 compiler Clang cpu_or_gpu GPU cpu_or_gpu_value TegraX1 extra_config Android model PixelC os Android; echo $? >/data/local/tmp/rc",
       "[START_DIR]/tmp/nanobench.sh"
     ],
     "env": {
diff --git a/infra/bots/recipes/perf.py b/infra/bots/recipes/perf.py
index b330fdc..96a2a3b 100644
--- a/infra/bots/recipes/perf.py
+++ b/infra/bots/recipes/perf.py
@@ -126,6 +126,11 @@
   args.append('--config')
   args.extend(configs)
 
+  # By default, we test with GPU threading enabled. Leave PixelC devices
+  # running without threads, just to get some coverage of that code path.
+  if 'PixelC' in bot:
+    args.extend(['--gpuThreads', '0'])
+
   if 'Valgrind' in bot:
     # Don't care about Valgrind performance.
     args.extend(['--loops',   '1'])
diff --git a/infra/bots/recipes/test.expected/Test-Android-Clang-PixelC-CPU-TegraX1-arm64-Debug-Android.json b/infra/bots/recipes/test.expected/Test-Android-Clang-PixelC-CPU-TegraX1-arm64-Debug-Android.json
index 66bef2c..d9e4516 100644
--- a/infra/bots/recipes/test.expected/Test-Android-Clang-PixelC-CPU-TegraX1-arm64-Debug-Android.json
+++ b/infra/bots/recipes/test.expected/Test-Android-Clang-PixelC-CPU-TegraX1-arm64-Debug-Android.json
@@ -706,7 +706,7 @@
       "--json-output",
       "/path/to/tmp/json",
       "copy",
-      "set -x; /data/local/tmp/dm --resourcePath /sdcard/revenge_of_the_skiabot/resources --skps /sdcard/revenge_of_the_skiabot/skps --images /sdcard/revenge_of_the_skiabot/images/dm --colorImages /sdcard/revenge_of_the_skiabot/images/colorspace --nameByHash --properties gitHash abc123 builder Test-Android-Clang-PixelC-CPU-TegraX1-arm64-Debug-Android swarming_bot_id skia-bot-123 swarming_task_id 123456 --svgs /sdcard/revenge_of_the_skiabot/svgs --key arch arm64 compiler Clang configuration Debug cpu_or_gpu CPU cpu_or_gpu_value TegraX1 extra_config Android model PixelC os Android --uninterestingHashesFile /sdcard/revenge_of_the_skiabot/uninteresting_hashes.txt --writePath /sdcard/revenge_of_the_skiabot/dm_out --dont_write pdf --ignoreSigInt --nogpu --config 8888 srgb serialize-8888 tiles_rt-8888 pic-8888 --src tests gm image colorImage --blacklist _ test _ GrShape serialize-8888 gm _ bleed_image serialize-8888 gm _ c_gms serialize-8888 gm _ colortype serialize-8888 gm _ colortype_xfermodes serialize-8888 gm _ drawfilter serialize-8888 gm _ fontmgr_bounds_0.75_0 serialize-8888 gm _ fontmgr_bounds_1_-0.25 serialize-8888 gm _ fontmgr_bounds serialize-8888 gm _ fontmgr_match serialize-8888 gm _ fontmgr_iter serialize-8888 gm _ imagemasksubset serialize-8888 gm _ bitmapfilters serialize-8888 gm _ bitmapshaders serialize-8888 gm _ bleed serialize-8888 gm _ bleed_alpha_bmp serialize-8888 gm _ bleed_alpha_bmp_shader serialize-8888 gm _ convex_poly_clip serialize-8888 gm _ extractalpha serialize-8888 gm _ filterbitmap_checkerboard_32_32_g8 serialize-8888 gm _ filterbitmap_image_mandrill_64 serialize-8888 gm _ shadows serialize-8888 gm _ simpleaaclip_aaclip serialize-8888 gm _ composeshader_bitmap serialize-8888 gm _ scaled_tilemodes_npot serialize-8888 gm _ scaled_tilemodes serialize-8888 gm _ typefacerendering_pfaMac serialize-8888 gm _ parsedpaths serialize-8888 gm _ ImageGeneratorExternal_rect serialize-8888 gm _ ImageGeneratorExternal_shader serialize-8888 gm _ shadow_utils serialize-8888 gm _ makecolorspace serialize-8888 gm _ bleed_alpha_image serialize-8888 gm _ bleed_alpha_image_shader serialize-8888 gm _ verylargebitmap serialize-8888 gm _ verylarge_picture_image pic-8888 gm _ drawfilter pic-8888 gm _ image-cacherator-from-picture serialize-8888 gm _ image-cacherator-from-picture pic-8888 gm _ image-cacherator-from-raster serialize-8888 gm _ image-cacherator-from-raster pic-8888 gm _ image-cacherator-from-ctable serialize-8888 gm _ image-cacherator-from-ctable pic-8888 gm _ gamut serialize-8888 gm _ gamut pic-8888 gm _ complexclip4_bw serialize-8888 gm _ complexclip4_bw pic-8888 gm _ complexclip4_aa serialize-8888 gm _ complexclip4_aa tiles_rt-8888 gm _ complexclip4_bw tiles_rt-8888 gm _ complexclip4_aa --verbose; echo $? >/data/local/tmp/rc",
+      "set -x; /data/local/tmp/dm --resourcePath /sdcard/revenge_of_the_skiabot/resources --skps /sdcard/revenge_of_the_skiabot/skps --images /sdcard/revenge_of_the_skiabot/images/dm --colorImages /sdcard/revenge_of_the_skiabot/images/colorspace --nameByHash --properties gitHash abc123 builder Test-Android-Clang-PixelC-CPU-TegraX1-arm64-Debug-Android swarming_bot_id skia-bot-123 swarming_task_id 123456 --svgs /sdcard/revenge_of_the_skiabot/svgs --key arch arm64 compiler Clang configuration Debug cpu_or_gpu CPU cpu_or_gpu_value TegraX1 extra_config Android model PixelC os Android --uninterestingHashesFile /sdcard/revenge_of_the_skiabot/uninteresting_hashes.txt --writePath /sdcard/revenge_of_the_skiabot/dm_out --dont_write pdf --ignoreSigInt --nogpu --config 8888 srgb serialize-8888 tiles_rt-8888 pic-8888 --src tests gm image colorImage --gpuThreads 0 --blacklist _ test _ GrShape serialize-8888 gm _ bleed_image serialize-8888 gm _ c_gms serialize-8888 gm _ colortype serialize-8888 gm _ colortype_xfermodes serialize-8888 gm _ drawfilter serialize-8888 gm _ fontmgr_bounds_0.75_0 serialize-8888 gm _ fontmgr_bounds_1_-0.25 serialize-8888 gm _ fontmgr_bounds serialize-8888 gm _ fontmgr_match serialize-8888 gm _ fontmgr_iter serialize-8888 gm _ imagemasksubset serialize-8888 gm _ bitmapfilters serialize-8888 gm _ bitmapshaders serialize-8888 gm _ bleed serialize-8888 gm _ bleed_alpha_bmp serialize-8888 gm _ bleed_alpha_bmp_shader serialize-8888 gm _ convex_poly_clip serialize-8888 gm _ extractalpha serialize-8888 gm _ filterbitmap_checkerboard_32_32_g8 serialize-8888 gm _ filterbitmap_image_mandrill_64 serialize-8888 gm _ shadows serialize-8888 gm _ simpleaaclip_aaclip serialize-8888 gm _ composeshader_bitmap serialize-8888 gm _ scaled_tilemodes_npot serialize-8888 gm _ scaled_tilemodes serialize-8888 gm _ typefacerendering_pfaMac serialize-8888 gm _ parsedpaths serialize-8888 gm _ ImageGeneratorExternal_rect serialize-8888 gm _ ImageGeneratorExternal_shader serialize-8888 gm _ shadow_utils serialize-8888 gm _ makecolorspace serialize-8888 gm _ bleed_alpha_image serialize-8888 gm _ bleed_alpha_image_shader serialize-8888 gm _ verylargebitmap serialize-8888 gm _ verylarge_picture_image pic-8888 gm _ drawfilter pic-8888 gm _ image-cacherator-from-picture serialize-8888 gm _ image-cacherator-from-picture pic-8888 gm _ image-cacherator-from-raster serialize-8888 gm _ image-cacherator-from-raster pic-8888 gm _ image-cacherator-from-ctable serialize-8888 gm _ image-cacherator-from-ctable pic-8888 gm _ gamut serialize-8888 gm _ gamut pic-8888 gm _ complexclip4_bw serialize-8888 gm _ complexclip4_bw pic-8888 gm _ complexclip4_aa serialize-8888 gm _ complexclip4_aa tiles_rt-8888 gm _ complexclip4_bw tiles_rt-8888 gm _ complexclip4_aa --verbose; echo $? >/data/local/tmp/rc",
       "[START_DIR]/tmp/dm.sh"
     ],
     "env": {
diff --git a/infra/bots/recipes/test.expected/Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Release-TSAN.json b/infra/bots/recipes/test.expected/Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Release-TSAN.json
index 5a72f11..b7fa0b6 100644
--- a/infra/bots/recipes/test.expected/Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Release-TSAN.json
+++ b/infra/bots/recipes/test.expected/Test-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Release-TSAN.json
@@ -177,8 +177,6 @@
       "gm",
       "image",
       "colorImage",
-      "--gpuThreads",
-      "8",
       "--blacklist",
       "f16",
       "_",
diff --git a/infra/bots/recipes/test.py b/infra/bots/recipes/test.py
index d33afc8..6262f4e 100644
--- a/infra/bots/recipes/test.py
+++ b/infra/bots/recipes/test.py
@@ -523,11 +523,15 @@
     match.extend(['~Once', '~Shared'])  # Not sure what's up with these tests.
 
   if 'TSAN' in bot:
-    args.extend(['--gpuThreads', '8'])
     match.extend(['~ReadWriteAlpha'])   # Flaky on TSAN-covered on nvidia bots.
     match.extend(['~RGBA4444TextureTest',  # Flakier than they are important.
                   '~RGB565TextureTest'])
 
+  # By default, we test with GPU threading enabled. Leave PixelC devices
+  # running without threads, just to get some coverage of that code path.
+  if 'PixelC' in bot:
+    args.extend(['--gpuThreads', '0'])
+
   if 'float_cast_overflow' in bot and 'CPU' in bot:
     # skia:4632
     for config in ['565', '8888', 'f16', 'srgb']:
diff --git a/tools/flags/SkCommonFlags.cpp b/tools/flags/SkCommonFlags.cpp
index c097f84..0fc1e1d 100644
--- a/tools/flags/SkCommonFlags.cpp
+++ b/tools/flags/SkCommonFlags.cpp
@@ -56,8 +56,8 @@
 DEFINE_int32_2(threads, j, -1, "Run threadsafe tests on a threadpool with this many extra threads, "
                                "defaulting to one extra thread per core.");
 
-DEFINE_int32(gpuThreads, 0, "Create this many extra threads to assist with GPU work, "
-                            "including software path rendering.");
+DEFINE_int32(gpuThreads, 2, "Create this many extra threads to assist with GPU work, "
+                            "including software path rendering. Defaults to two.");
 
 DEFINE_bool2(verbose, v, false, "enable verbose output from the test driver.");