From b7683155517c09c7e0f9d791eaab6dab3b4b2477 Mon Sep 17 00:00:00 2001 From: Edward Cree Date: Mon, 17 Feb 2020 13:43:10 +0000 Subject: [PATCH] sfc: only schedule asynchronous filter work if needed Prevent excessive CPU time spent running a workitem with nothing to do. We avoid any races by keeping the same check in efx_filter_rfs_expire(). Suggested-by: Martin Habets Signed-off-by: Edward Cree Signed-off-by: David S. Miller --- drivers/net/ethernet/sfc/efx.h | 2 +- drivers/net/ethernet/sfc/efx_channels.c | 8 +++++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h index f1bdb04..78babbe 100644 --- a/drivers/net/ethernet/sfc/efx.h +++ b/drivers/net/ethernet/sfc/efx.h @@ -159,7 +159,7 @@ static inline void efx_filter_rfs_expire(struct work_struct *data) channel = container_of(dwork, struct efx_channel, filter_work); time = jiffies - channel->rfs_last_expiry; quota = channel->rfs_filter_count * time / (30 * HZ); - if (quota > 20 && __efx_filter_rfs_expire(channel, min(channel->rfs_filter_count, quota))) + if (quota >= 20 && __efx_filter_rfs_expire(channel, min(channel->rfs_filter_count, quota))) channel->rfs_last_expiry += time; /* Ensure we do more work eventually even if NAPI poll is not happening */ schedule_delayed_work(dwork, 30 * HZ); diff --git a/drivers/net/ethernet/sfc/efx_channels.c b/drivers/net/ethernet/sfc/efx_channels.c index aeb5e8a..1b1265d 100644 --- a/drivers/net/ethernet/sfc/efx_channels.c +++ b/drivers/net/ethernet/sfc/efx_channels.c @@ -1166,6 +1166,9 @@ static int efx_poll(struct napi_struct *napi, int budget) struct efx_channel *channel = container_of(napi, struct efx_channel, napi_str); struct efx_nic *efx = channel->efx; +#ifdef CONFIG_RFS_ACCEL + unsigned int time; +#endif int spent; netif_vdbg(efx, intr, efx->net_dev, @@ -1185,7 +1188,10 @@ static int efx_poll(struct napi_struct *napi, int budget) #ifdef CONFIG_RFS_ACCEL /* Perhaps expire some ARFS filters */ - mod_delayed_work(system_wq, &channel->filter_work, 0); + time = jiffies - channel->rfs_last_expiry; + /* Would our quota be >= 20? */ + if (channel->rfs_filter_count * time >= 600 * HZ) + mod_delayed_work(system_wq, &channel->filter_work, 0); #endif /* There is no race here; although napi_disable() will -- 2.7.4