[PATCH net-next v2 06/11] net: ethernet: cortina: Rotate free queue page allocation
WARM2d
From: Linus Walleij <linusw@kernel.org>
Date: 2026-09-28 08:50:56
Subsystem:
arm/cortina systems gemini arm architecture, networking drivers, the rest · Maintainers:
Hans Ulli Kroll, Linus Walleij, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The free queue metadata bitmap currently searches for a free slot from zero for every page allocation. Under sustained traffic this repeatedly scans occupied low-numbered slots. Remember the position after the most recently allocated slot and wrap the bitmap search at its end. This keeps allocation cost distributed across the metadata table. Assisted-by: LLM Signed-off-by: Linus Walleij <linusw@kernel.org> --- drivers/net/ethernet/cortina/gemini.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c
index 8d216fa45287..385b78fd6653 100644
--- a/drivers/net/ethernet/cortina/gemini.c
+++ b/drivers/net/ethernet/cortina/gemini.c@@ -172,6 +172,7 @@ struct gemini_ethernet { struct xarray freeq_mappings; unsigned int num_freeq_pages; unsigned long *freeq_page_bitmap; + unsigned int freeq_page_cursor; spinlock_t freeq_lock; /* Locks queue from reentrance */ };
@@ -743,12 +744,20 @@ static int geth_freeq_alloc_slot(struct gemini_ethernet *geth) lockdep_assert_held(&geth->freeq_lock); - slot = find_first_zero_bit(geth->freeq_page_bitmap, - geth->num_freeq_pages); - if (slot == geth->num_freeq_pages) - return -ENOSPC; + slot = find_next_zero_bit(geth->freeq_page_bitmap, + geth->num_freeq_pages, + geth->freeq_page_cursor); + if (slot == geth->num_freeq_pages) { + slot = find_first_zero_bit(geth->freeq_page_bitmap, + geth->freeq_page_cursor); + if (slot == geth->freeq_page_cursor) + return -ENOSPC; + } __set_bit(slot, geth->freeq_page_bitmap); + geth->freeq_page_cursor = slot + 1; + if (geth->freeq_page_cursor == geth->num_freeq_pages) + geth->freeq_page_cursor = 0; return slot; }
@@ -1072,6 +1081,7 @@ static int geth_setup_freeq(struct gemini_ethernet *geth) if (!geth->freeq_page_bitmap) goto err_freeq_pages; geth->num_freeq_pages = page_slots; + geth->freeq_page_cursor = 0; expected = len - (1 << fpp_order); filled = geth_fill_freeq(geth);
--
2.55.0