Mingming Cao 3c14917953 ibmvnic: Increase max subcrq indirect entries with fallback ... POWER8 support a maximum of 16 subcrq indirect descriptor entries per H_SEND_SUB_CRQ_INDIRECT call, while POWER9 and newer hypervisors support up to 128 entries. Increasing the max number of indirect descriptor entries improves batching efficiency and reduces hcall overhead, which enhances throughput under large workload on POWER9+. Currently, ibmvnic driver always uses a fixed number of max indirect descriptor entries (16). send_subcrq_indirect() treats all hypervisor errors the same: - Cleanup and Drop the entire batch of descriptors. - Return an error to the caller. - Rely on TCP/IP retransmissions to recover. - If the hypervisor returns H_PARAMETER (e.g., because 128 entries are not supported on POWER8), the driver will continue to drop batches, resulting in unnecessary packet loss. In this patch: Raise the default maximum indirect entries to 128 to improve ibmvnic batching on morden platform. But also gracefully fall back to 16 entries for Power 8 systems. Since there is no VIO interface to query the hypervisor’s supported limit, vnic handles send_subcrq_indirect() H_PARAMETER errors: - On first H_PARAMETER failure, log the failure context - Reduce max_indirect_entries to 16 and allow the single batch to drop. - Subsequent calls automatically use the correct lower limit, avoiding repeated drops. The goal is to optimizes performance on modern systems while handles falling back for older POWER8 hypervisors. Performance shows 40% improvements with MTU (1500) on largework load. Signed-off-by: Mingming Cao <mmc@linux.ibm.com> Reviewed-by: Brian King <bjking1@linux.ibm.com> Reviewed-by: Haren Myneni <haren@linux.ibm.com> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20250821130215.97960-1-mmc@linux.ibm.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>		2025-08-26 09:45:50 +02:00
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ehea	net: ethernet: Switch back to struct platform_driver::remove()	2024-10-04 16:39:56 -07:00
emac	net: ibm: emac: Use of_get_available_child_by_name()	2025-02-07 13:43:55 +00:00
ibmveth.c	ibmveth: Add multi buffers rx replenishment hcall support	2025-07-22 15:08:23 +02:00
ibmveth.h	ibmveth: Add multi buffers rx replenishment hcall support	2025-07-22 15:08:23 +02:00
ibmvnic.c	ibmvnic: Increase max subcrq indirect entries with fallback	2025-08-26 09:45:50 +02:00
ibmvnic.h	ibmvnic: Increase max subcrq indirect entries with fallback	2025-08-26 09:45:50 +02:00
Kconfig	net: ibmveth: added KUnit tests for some buffer pool functions	2025-05-06 10:24:38 +02:00
Makefile