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[149.6.153.186]) by smtp.gmail.com with ESMTPSA id r3sm4715994wrr.61.2019.06.14.05.46.38 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 14 Jun 2019 05:46:38 -0700 (PDT) Date: Fri, 14 Jun 2019 14:46:36 +0200 From: Lorenzo Bianconi To: Stanislaw Gruszka Cc: Lorenzo Bianconi , kvalo@codeaurora.org, linux-wireless@vger.kernel.org, nbd@nbd.name Subject: Re: [PATCH v3 wireless-drivers 3/3] mt76: usb: do not always copy the first part of received frames Message-ID: <20190614124635.GD2669@localhost.localdomain> References: <1a9566c0a41ad0d940487a9d3f0008993c075ef2.1560461404.git.lorenzo@kernel.org> <20190614075303.GB3395@redhat.com> <20190614102247.GB2669@localhost.localdomain> <20190614110442.GA17298@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="lc9FT7cWel8HagAv" Content-Disposition: inline In-Reply-To: <20190614110442.GA17298@redhat.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org --lc9FT7cWel8HagAv Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > On Fri, Jun 14, 2019 at 12:22:48PM +0200, Lorenzo Bianconi wrote: > > > On Thu, Jun 13, 2019 at 11:43:13PM +0200, Lorenzo Bianconi wrote: > > > > Set usb buffer size taking into account skb_shared_info in order to > > > > not always copy the first part of received frames if A-MSDU is enab= led > > > > for SG capable devices. Moreover align usb buffer size to max_ep > > > > boundaries and set buf_size to PAGE_SIZE even for sg case > > >=20 > > > I think this should not be applied to wirless-drivers, only first pat= ch > > > that fix the bug and optimizations should be done in -next. > >=20 > > ack, right. I think patch 2/3 and 3/3 can go directly in Felix's tree > >=20 > > >=20 > > > > + int i, data_size; > > > > =20 > > > > + data_size =3D rounddown(SKB_WITH_OVERHEAD(q->buf_size), > > > > + dev->usb.in_ep[MT_EP_IN_PKT_RX].max_packet); > > > > for (i =3D 0; i < nsgs; i++) { > > > > struct page *page; > > > > void *data; > > > > @@ -302,7 +304,7 @@ mt76u_fill_rx_sg(struct mt76_dev *dev, struct m= t76_queue *q, struct urb *urb, > > > > =20 > > > > page =3D virt_to_head_page(data); > > > > offset =3D data - page_address(page); > > > > - sg_set_page(&urb->sg[i], page, q->buf_size, offset); > > > > + sg_set_page(&urb->sg[i], page, data_size, offset); > > > > > > > - q->buf_size =3D dev->usb.sg_en ? MT_RX_BUF_SIZE : PAGE_SIZE; > > > > q->ndesc =3D MT_NUM_RX_ENTRIES; > > > > + q->buf_size =3D PAGE_SIZE; > > > > + > > >=20 > > > This should be associated with decrease of MT_SG_MAX_SIZE to value th= at > > > is actually needed and currently this is 2 for 4k AMSDU. > >=20 > > MT_SG_MAX_SIZE is used even on tx side and I do not think we will end u= p with a > > huge difference here >=20 > So use different value as argument for mt76u_fill_rx_sg() in > mt76u_rx_urb_alloc(). After changing buf_size to PAGE_SIZE we will > allocate 8 pages per rx queue entry, but only 2 pages will be used > (with data_size change, 1 without data_size change). Or I'm wrong? yes, it is right (we will use two pages with data_size change). Maybe bette= r to use 4 pages for each rx queue entry? (otherwise we will probably change it = in the future) >=20 > > > However I don't think allocating 2 pages to avoid ieee80211 header an= d SNAP > > > copy is worth to do. For me best approach would be allocate 1 page for > > > 4k AMSDU, 2 for 8k and 3 for 12k (still using sg, but without data_si= ze > > > change to avoid 32B copying). > >=20 > > From my point of view it is better to avoid copying if it is possible. = Are you > > sure there is no difference? >=20 > I do not understand what you mean by difference here. tpt differences, not sure if there are any Regards, Lorenzo >=20 > Stanislaw --lc9FT7cWel8HagAv Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCXQOXKAAKCRA6cBh0uS2t rB7QAQCfJt10qzCycycy6teI+eEpLE4CpHVuDrxLhG8au3oHfAD+Ikwz4MStc1UG D31AjocPFjIh8yEFmfvU9dPYGQl9vAo= =XVwB -----END PGP SIGNATURE----- --lc9FT7cWel8HagAv--