Re: [PATCH net-next v4 1/6] ibmvnic: Move long delayed work on system_dfl_long_wq
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From: mingming cao <hidden>
Date: 2026-10-16 21:20:24
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On 10/12/26 2:54 AM, Marco Crivellari wrote:
quoted hunk ↗ jump to hunk
Currently the code enqueue work items using {queue|mod}_delayed_work(), using system_long_wq. This workqueue should be used when long works are expected and it is a per-cpu workqueue. The function(s) end up calling __queue_delayed_work(), which set a global timer that could fire anywhere, enqueuing the work where the timer fired. Unbound works could benefit from scheduler task placement, to optimize performance and power consumption. Long work shouldn't stick to a single CPU. Recently, a new unbound workqueue specific for long running work has been added: c116737e972e ("workqueue: Add system_dfl_long_wq for long unbound works") Since the workqueue work doesn't rely on per-cpu variables, there is no obvious reason that justify the use of a per-cpu workqueue. So change system_long_wq with system_dfl_long_wq so that the work may benefit from scheduler task placement. Cc: Haren Myneni <haren@linux.ibm.com> Cc: Rick Lindsley <ricklind@linux.ibm.com> Cc: Nick Child <nnac123@linux.ibm.com> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Christophe Leroy (CS GROUP) <chleroy@kernel.org> Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Marco Crivellari <redacted> --- drivers/net/ethernet/ibm/ibmvnic.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c index 5a510eed335e..d4c284c8ef43 100644 --- a/drivers/net/ethernet/ibm/ibmvnic.c +++ b/drivers/net/ethernet/ibm/ibmvnic.c@@ -3229,7 +3229,7 @@ static void __ibmvnic_reset(struct work_struct *work) if (adapter->state == VNIC_PROBING && !wait_for_completion_timeout(&adapter->probe_done, timeout)) { dev_err(dev, "Reset thread timed out on probe"); - queue_delayed_work(system_long_wq, + queue_delayed_work(system_dfl_long_wq, &adapter->ibmvnic_delayed_reset, IBMVNIC_RESET_DELAY); return;@@ -3267,7 +3267,7 @@ static void __ibmvnic_reset(struct work_struct *work) spin_lock(&adapter->rwi_lock); if (!list_empty(&adapter->rwi_list)) { if (test_and_set_bit_lock(0, &adapter->resetting)) { - queue_delayed_work(system_long_wq, + queue_delayed_work(system_dfl_long_wq, &adapter->ibmvnic_delayed_reset, IBMVNIC_RESET_DELAY); } else {@@ -3454,7 +3454,7 @@ static int ibmvnic_reset(struct ibmvnic_adapter *adapter, list_add_tail(&rwi->list, &adapter->rwi_list); netdev_dbg(adapter->netdev, "Scheduling reset (reason %s)\n", reset_reason_to_string(reason)); - queue_work(system_long_wq, &adapter->ibmvnic_reset); + queue_work(system_dfl_long_wq, &adapter->ibmvnic_reset); ret = 0; err:
On 10/12/26 2:54 AM, Marco Crivellari wrote:
quoted hunk ↗ jump to hunk
Currently the code enqueue work items using {queue|mod}_delayed_work(), using system_long_wq. This workqueue should be used when long works are expected and it is a per-cpu workqueue. The function(s) end up calling __queue_delayed_work(), which set a global timer that could fire anywhere, enqueuing the work where the timer fired. Unbound works could benefit from scheduler task placement, to optimize performance and power consumption. Long work shouldn't stick to a single CPU. Recently, a new unbound workqueue specific for long running work has been added: c116737e972e ("workqueue: Add system_dfl_long_wq for long unbound works") Since the workqueue work doesn't rely on per-cpu variables, there is no obvious reason that justify the use of a per-cpu workqueue. So change system_long_wq with system_dfl_long_wq so that the work may benefit from scheduler task placement. Cc: Haren Myneni <haren@linux.ibm.com> Cc: Rick Lindsley <ricklind@linux.ibm.com> Cc: Nick Child <nnac123@linux.ibm.com> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Christophe Leroy (CS GROUP) <chleroy@kernel.org> Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Marco Crivellari <redacted> --- drivers/net/ethernet/ibm/ibmvnic.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c index 5a510eed335e..d4c284c8ef43 100644 --- a/drivers/net/ethernet/ibm/ibmvnic.c +++ b/drivers/net/ethernet/ibm/ibmvnic.c@@ -3229,7 +3229,7 @@ static void __ibmvnic_reset(struct work_struct *work) if (adapter->state == VNIC_PROBING && !wait_for_completion_timeout(&adapter->probe_done, timeout)) { dev_err(dev, "Reset thread timed out on probe"); - queue_delayed_work(system_long_wq, + queue_delayed_work(system_dfl_long_wq, &adapter->ibmvnic_delayed_reset, IBMVNIC_RESET_DELAY); return;@@ -3267,7 +3267,7 @@ static void __ibmvnic_reset(struct work_struct *work) spin_lock(&adapter->rwi_lock); if (!list_empty(&adapter->rwi_list)) { if (test_and_set_bit_lock(0, &adapter->resetting)) { - queue_delayed_work(system_long_wq, + queue_delayed_work(system_dfl_long_wq, &adapter->ibmvnic_delayed_reset, IBMVNIC_RESET_DELAY); } else {@@ -3454,7 +3454,7 @@ static int ibmvnic_reset(struct ibmvnic_adapter *adapter, list_add_tail(&rwi->list, &adapter->rwi_list); netdev_dbg(adapter->netdev, "Scheduling reset (reason %s)\n", reset_reason_to_string(reason)); - queue_work(system_long_wq, &adapter->ibmvnic_reset); + queue_work(system_dfl_long_wq, &adapter->ibmvnic_reset); ret = 0; err:
I walked through the reset path and the conversion looks fine. All three system_long_wq users move together and there are no remaining users in the driver. The work items don't rely on per-CPU state, so system_dfl_long_wq seems appropriate here. Minor commit message nit: ibmvnic doesn't use mod_delayed_work(), and one of the conversions is queue_work() rather than delayed work. Acked-by: Mingming Cao <redacted>