> On Mon, Jul 5, 2021 at 8:52 AM Lorenzo Bianconi > <lorenzo.bianconi@xxxxxxxxxx> wrote: > > > > > On Tue, Jun 29, 2021 at 5:43 AM Lorenzo Bianconi > > > <lorenzo.bianconi@xxxxxxxxxx> wrote: [...] > > Hi Lorenzo, > > What about doing something like breaking up the type value in > xdp_mem_info? The fact is having it as an enum doesn't get us much > since we have a 32b type field but are only storing 4 possible values > there currently > > The way I see it, scatter-gather is just another memory model > attribute rather than being something entirely new. It makes as much > sense to have a bit there for MEM_TYPE_PAGE_SG as it does for > MEM_TYPE_PAGE_SHARED. I would consider either splitting the type field > into two 16b fields. For example you might have one field that > describes the source pool which is currently either allocated page > (ORDER0, SHARED), page_pool (PAGE_POOL), or XSK pool (XSK_BUFF_POOL), > and then two flags for type with there being either shared and/or > scatter-gather. Hi Alex, I am fine reducing the xdp_mem_info size defining type field as u16 instead of u32 but I think mb is a per-xdp_buff/xdp_frame property since at runtime we can receive a tiny single page xdp_buff/xdp_frame and a "jumbo" xdp_buff/xdp_frame composed by multiple pages. According to the documentation available in include/net/xdp.h, xdp_rxq_info (where xdp_mem_info is contained for xdp_buff) is "associated with the driver level RX-ring queues and it is information that is specific to how the driver have configured a given RX-ring queue" so I guess it is a little bit counterintuitive to add this info there. Moreover we have the "issue" for devmap in dev_map_bpf_prog_run() when we perform XDP_REDIRECT with the approach you proposed and last we can reuse this new flags filed for XDP hw-hints support. What about reducing xdp_mem_info and add the flags field in xdp_buff/xdp_frame in order to avoid increasing the xdp_buff/xdp_frame size? Am I missing something? Regards, Lorenzo > > Also, looking over the code I don't see any reason why current > ORDER0/SHARED couldn't be merged as the free paths are essentially > identical since the MEM_TYPE_PAGE_SHARED path would function perfectly > fine to free MEM_TYPE_PAGE_ORDER0 pages. > > Thanks, > > - Alex >
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