From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0404F22424E for ; Wed, 16 Apr 2025 18:42:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744828939; cv=none; b=SDbFk+W2tCljJ6/qe0EGwVxpPEJJrMOryah8WAgMc8ADAb9oyqMPYgOIK/BObrBA3zSasMtdrphpUY9Sy9OaFeB0kW5+MYFM/6R+qQab40T90l2VnBbtPIP8n7S4HjM+YiXe5cuVGgltE2qUN5B2QZO/pJB7IAFPp0KeBa/Pd7g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744828939; c=relaxed/simple; bh=gM9Vxni7W754ZNMFRPyZuP3ZsAloFTWS+oW7brATXIw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=gdyJ5NHji2CVkgPlaBSjtnwVR1qv+bKdklBG+IXf3am/eE9l7dPFThrMDDBftJvqNoXdtxeFDsO8j2fOYixzqq7k4VjOXsVGVevY6w6rgv7QRPBlA0SgRGztDlCvxoS/2oVo/srI3YH3zsS8Q2HfzalnwsFCxxshUUMfOk7R4cA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XQ/XKBBI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XQ/XKBBI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38E70C4CEE2; Wed, 16 Apr 2025 18:42:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744828938; bh=gM9Vxni7W754ZNMFRPyZuP3ZsAloFTWS+oW7brATXIw=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=XQ/XKBBID+iMGKjXAl+KpPnZmzvPGGwsUaf8v8y3hp6eClrJoLHJOYAzz5lof6IeQ crCewTHlFJB2TuBY6yXDsQsuK4fh0TusIZqCIOkkUSUHxi+zelFYn+tfJvhMPHKr7t JTjls/4tr/8RtRcG3djiohls8RWvdyJ8xiEtbg1QLx6jEveuR6Fjx3IEUlmS7uLqCs MPLgpIOvN8Fv/1ynTt0KC27CCLUUBdV+r/t7VNuA1OBAxiH8AFNBCP1adxHEAlKGM0 0b5ozFsAKp1XBinUKlrj9n5eAkkLYBymrJUN70LlSoGctpcex4hLTgoG8pnw2F/g1U z19pQSl+0JT5Q== Message-ID: <1086d2ecc8fc0aed85fc571e8bc4c66f6ff0fb64.camel@kernel.org> Subject: Re: [RFC PATCH 1/2] sunrpc: Replace the rq_bvec array with dynamically-allocated memory From: Jeff Layton To: cel@kernel.org, NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, Chuck Lever Date: Wed, 16 Apr 2025 14:42:17 -0400 In-Reply-To: <20250416152854.15269-2-cel@kernel.org> References: <20250416152854.15269-1-cel@kernel.org> <20250416152854.15269-2-cel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Wed, 2025-04-16 at 11:28 -0400, cel@kernel.org wrote: > From: Chuck Lever >=20 > As a step towards making NFSD's maximum rsize and wsize variable, > replace the fixed-size rq_bvec[] array in struct svc_rqst with a > chunk of dynamically-allocated memory. >=20 > On a system with 8-byte pointers and 4KB pages, pahole reports that > the rq_bvec[] array is 4144 bytes. Replacing it with a single > pointer reduces the size of struct svc_rqst to about 7500 bytes. >=20 > Signed-off-by: Chuck Lever > --- > include/linux/sunrpc/svc.h | 2 +- > net/sunrpc/svc.c | 6 ++++++ > net/sunrpc/svcsock.c | 7 +++---- > 3 files changed, 10 insertions(+), 5 deletions(-) >=20 > diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h > index 74658cca0f38..225c385085c3 100644 > --- a/include/linux/sunrpc/svc.h > +++ b/include/linux/sunrpc/svc.h > @@ -195,7 +195,7 @@ struct svc_rqst { > =20 > struct folio_batch rq_fbatch; > struct kvec rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */ > - struct bio_vec rq_bvec[RPCSVC_MAXPAGES]; > + struct bio_vec *rq_bvec; It's a reasonable start. What would also be good to do here is to replace the invocations of RPCSVC_MAXPAGES that involve this array with a helper function that returns the length of it. For now it could just return RPCSVC_MAXPAGES, but eventually you could add (e.g.) a rqstp->rq_bvec_len field and use that to indicate how many entries there are in rq_bvec. > =20 > __be32 rq_xid; /* transmission id */ > u32 rq_prog; /* program number */ > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > index e7f9c295d13c..db29819716b8 100644 > --- a/net/sunrpc/svc.c > +++ b/net/sunrpc/svc.c > @@ -673,6 +673,7 @@ static void > svc_rqst_free(struct svc_rqst *rqstp) > { > folio_batch_release(&rqstp->rq_fbatch); > + kfree(rqstp->rq_bvec); > svc_release_buffer(rqstp); > if (rqstp->rq_scratch_page) > put_page(rqstp->rq_scratch_page); > @@ -711,6 +712,11 @@ svc_prepare_thread(struct svc_serv *serv, struct svc= _pool *pool, int node) > if (!svc_init_buffer(rqstp, serv->sv_max_mesg, node)) > goto out_enomem; > =20 > + rqstp->rq_bvec =3D kcalloc_node(RPCSVC_MAXPAGES, sizeof(struct bio_vec)= , > + GFP_KERNEL, node); > + if (!rqstp->rq_bvec) > + goto out_enomem; > + > rqstp->rq_err =3D -EAGAIN; /* No error yet */ > =20 > serv->sv_nrthreads +=3D 1; > diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c > index 72e5a01df3d3..671640933f18 100644 > --- a/net/sunrpc/svcsock.c > +++ b/net/sunrpc/svcsock.c > @@ -713,8 +713,7 @@ static int svc_udp_sendto(struct svc_rqst *rqstp) > if (svc_xprt_is_dead(xprt)) > goto out_notconn; > =20 > - count =3D xdr_buf_to_bvec(rqstp->rq_bvec, > - ARRAY_SIZE(rqstp->rq_bvec), xdr); > + count =3D xdr_buf_to_bvec(rqstp->rq_bvec, RPCSVC_MAXPAGES, xdr); > =20 > iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, rqstp->rq_bvec, > count, rqstp->rq_res.len); > @@ -1219,8 +1218,8 @@ static int svc_tcp_sendmsg(struct svc_sock *svsk, s= truct svc_rqst *rqstp, > memcpy(buf, &marker, sizeof(marker)); > bvec_set_virt(rqstp->rq_bvec, buf, sizeof(marker)); > =20 > - count =3D xdr_buf_to_bvec(rqstp->rq_bvec + 1, > - ARRAY_SIZE(rqstp->rq_bvec) - 1, &rqstp->rq_res); > + count =3D xdr_buf_to_bvec(rqstp->rq_bvec + 1, RPCSVC_MAXPAGES, > + &rqstp->rq_res); > =20 > iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, rqstp->rq_bvec, > 1 + count, sizeof(marker) + rqstp->rq_res.len); --=20 Jeff Layton