diff mbox series

net: netvsc: Increase default VMBus channel from 8 to 16

Message ID 1722923751-27296-1-git-send-email-ernis@linux.microsoft.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series net: netvsc: Increase default VMBus channel from 8 to 16 | expand

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Context Check Description
netdev/series_format warning Single patches do not need cover letters; Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 29 this patch: 29
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 29 this patch: 29
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 29 this patch: 29
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-08-06--15-00 (tests: 707)

Commit Message

Erni Sri Satya Vennela Aug. 6, 2024, 5:55 a.m. UTC 
Increase default VMBus channels in Linux netvsc from 8 to 16
to align with Azure Windows VM and improve networking throughput.

Set channels to 16 for VMs with more than 16 vCPUs;
otherwise, channels depend on VM's vCPU count.

Performance tests showed significant improvement in throughput:
- 0.54% for 16 vCPUs
- 1.51% for 32 vCPUs
- 0.72% for 48 vCPUs
- 5.57% for 64 vCPUs
- 9.14% for 96 vCPUs

Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
Reviewed-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
---
 drivers/net/hyperv/hyperv_net.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Jakub Kicinski Aug. 8, 2024, 3:18 a.m. UTC | #1 
On Mon,  5 Aug 2024 22:55:51 -0700 Erni Sri Satya Vennela wrote:
> Performance tests showed significant improvement in throughput:
> - 0.54% for 16 vCPUs
> - 1.51% for 32 vCPUs
> - 0.72% for 48 vCPUs
> - 5.57% for 64 vCPUs
> - 9.14% for 96 vCPUs

Could you please switch to netif_get_num_default_rss_queues() ?
It used to return hard coded 8, but now it returns #physical cores / 2.
That's based on broad experience with Meta's workloads. Some workloads
need more some needs fewer, but broadly half of physical cores is
a good guess for 90%+
Assuming you have thread siblings in those vCPUs above it should
match what you want, too.
diff mbox series

Patch

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 810977952f95..e690b95b1bbb 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -882,7 +882,7 @@  struct nvsp_message {
 
 #define VRSS_SEND_TAB_SIZE 16  /* must be power of 2 */
 #define VRSS_CHANNEL_MAX 64
-#define VRSS_CHANNEL_DEFAULT 8
+#define VRSS_CHANNEL_DEFAULT 16
 
 #define RNDIS_MAX_PKT_DEFAULT 8
 #define RNDIS_PKT_ALIGN_DEFAULT 8