From: Lorenzo Bianconi <lorenzo@xxxxxxxxxx> Date: Fri, 12 May 2023 15:08:13 +0200 > In order to reduce page_pool memory footprint, rely on > page_pool_dev_alloc_frag routine and reduce buffer size > (VETH_PAGE_POOL_FRAG_SIZE) to PAGE_SIZE / 2 in order to consume one page > for two 1500B frames. Reduce VETH_XDP_PACKET_HEADROOM to 192 from 256 > (XDP_PACKET_HEADROOM) to fit max_head_size in VETH_PAGE_POOL_FRAG_SIZE. > Please note, using default values (CONFIG_MAX_SKB_FRAGS=17), maximum > supported MTU is now reduced to 36350B. I thought we're stepping away from page splitting bit by bit O_o Primarily for the reasons you mentioned / worked around here: it creates several significant limitations and at least on 64-bit systems it doesn't scale anymore. 192 bytes of headroom is less than what XDP expects (isn't it? Isn't 256 standard-standard, so that skb XDP path reallocates heads only to have 256+ there?), 384 bytes of shinfo can change anytime and even now page split simply blocks you from increasing MAX_SKB_FRAGS even by one. Not speaking of MTU limitations etc. BTW Intel drivers suffer from the very same things due solely to page split (and I'm almost done with converting at least some of them to Page Pool and 1 page per buffer model), I don't recommend deliberately falling into that pit =\ :D > > Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx> > --- > drivers/net/veth.c | 39 +++++++++++++++++++++++++-------------- > 1 file changed, 25 insertions(+), 14 deletions(-) [...] Thanks, Olek
