linux-kernel - Re: [PATCH net-next v4] net: mana: Implement get_ringparam/set

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Message-ID: <20240826034032.GA1883@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
Date: Sun, 25 Aug 2024 20:40:32 -0700
From: Shradha Gupta <shradhagupta@...ux.microsoft.com>
To: Saurabh Singh Sengar <ssengar@...ux.microsoft.com>
Cc: linux-hyperv@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Long Li <longli@...rosoft.com>, Simon Horman <horms@...nel.org>,
	Konstantin Taranov <kotaranov@...rosoft.com>,
	Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>,
	Erick Archer <erick.archer@...look.com>,
	Pavan Chebbi <pavan.chebbi@...adcom.com>,
	Ahmed Zaki <ahmed.zaki@...el.com>,
	Colin Ian King <colin.i.king@...il.com>,
	Shradha Gupta <shradhagupta@...rosoft.com>
Subject: Re: [PATCH net-next v4] net: mana: Implement
 get_ringparam/set_ringparam for mana

On Fri, Aug 23, 2024 at 04:34:54AM -0700, Saurabh Singh Sengar wrote:
> On Thu, Aug 22, 2024 at 08:53:09AM -0700, Shradha Gupta wrote:
> > Currently the values of WQs for RX and TX queues for MANA devices
> > are hardcoded to default sizes.
> > Allow configuring these values for MANA devices as ringparam
> > configuration(get/set) through ethtool_ops.
> > Pre-allocate buffers at the beginning of this operation, to
> > prevent complete network loss in low-memory conditions.
> > 
> > Signed-off-by: Shradha Gupta <shradhagupta@...ux.microsoft.com>
> > Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>
> > ---
> >  Changes in v4:
> >  * Roundup the ring parameter value to a power of 2
> >  * Skip the max value check for parameters
> >  * Use extack to log errors
> > ---
> >  Changes in v3:
> >  * pre-allocate buffers before changing the queue sizes
> >  * rebased to latest net-next
> > ---
> >  Changes in v2:
> >  * Removed unnecessary validations in mana_set_ringparam()
> >  * Fixed codespell error
> >  * Improved error message to indicate issue with the parameter
> > ---
> >  drivers/net/ethernet/microsoft/mana/mana_en.c | 24 +++---
> >  .../ethernet/microsoft/mana/mana_ethtool.c    | 74 +++++++++++++++++++
> >  include/net/mana/mana.h                       | 23 +++++-
> >  3 files changed, 108 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > index d2f07e179e86..4e3ade5926bc 100644
> > --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> > +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > @@ -511,7 +511,7 @@ static u16 mana_select_queue(struct net_device *ndev, struct sk_buff *skb,
> >  }
> >  
> >  /* Release pre-allocated RX buffers */
> > -static void mana_pre_dealloc_rxbufs(struct mana_port_context *mpc)
> > +void mana_pre_dealloc_rxbufs(struct mana_port_context *mpc)
> >  {
> >  	struct device *dev;
> >  	int i;
> > @@ -604,7 +604,7 @@ static void mana_get_rxbuf_cfg(int mtu, u32 *datasize, u32 *alloc_size,
> >  	*datasize = mtu + ETH_HLEN;
> >  }
> >  
> > -static int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, int new_mtu)
> > +int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, int new_mtu)
> >  {
> >  	struct device *dev;
> >  	struct page *page;
> > @@ -618,7 +618,7 @@ static int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, int new_mtu)
> >  
> >  	dev = mpc->ac->gdma_dev->gdma_context->dev;
> >  
> > -	num_rxb = mpc->num_queues * RX_BUFFERS_PER_QUEUE;
> > +	num_rxb = mpc->num_queues * mpc->rx_queue_size;
> >  
> >  	WARN(mpc->rxbufs_pre, "mana rxbufs_pre exists\n");
> >  	mpc->rxbufs_pre = kmalloc_array(num_rxb, sizeof(void *), GFP_KERNEL);
> > @@ -1899,14 +1899,15 @@ static int mana_create_txq(struct mana_port_context *apc,
> >  		return -ENOMEM;
> >  
> >  	/*  The minimum size of the WQE is 32 bytes, hence
> > -	 *  MAX_SEND_BUFFERS_PER_QUEUE represents the maximum number of WQEs
> > +	 *  apc->tx_queue_size represents the maximum number of WQEs
> >  	 *  the SQ can store. This value is then used to size other queues
> >  	 *  to prevent overflow.
> > +	 *  Also note that the txq_size is always going to be MANA_PAGE_ALIGNED,
> > +	 *  as tx_queue_size is always a power of 2.
> >  	 */
> 
> 	MANA_PAGE_ALIGNED aligned means aligned by 0x1000. tx_queue_size being
> 	'power of 2' * 32 is not a sufficient condition for it to be aligned to
> 	0x1000. We possibly can explain more.
> 
> 
> > -	txq_size = MAX_SEND_BUFFERS_PER_QUEUE * 32;
> > -	BUILD_BUG_ON(!MANA_PAGE_ALIGNED(txq_size));
> > +	txq_size = apc->tx_queue_size * 32;
> >  
> > -	cq_size = MAX_SEND_BUFFERS_PER_QUEUE * COMP_ENTRY_SIZE;
> > +	cq_size = apc->tx_queue_size * COMP_ENTRY_SIZE;
> >  	cq_size = MANA_PAGE_ALIGN(cq_size);
> 
> 	COMP_ENTRY_SIZE is 64, that means cq_size is double of txq_size.
> 	If we are certain that txq_size is always aligned to MANA_PAGE,
> 	that means cq_size is already aligned to MANA_PAGE as well.
> 
> - Saurabh
Thanks Saurabh.

I'll incorporate these in the next version