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 9DF0826462E for ; Mon, 21 Apr 2025 12:22:42 +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=1745238163; cv=none; b=B4RIXQ8rM4cRfKLCU5AweRvfBrNh313xLBCsc1ER1G62GiEnd2u1Y+yaIonnrRn4P8+6dPVq2NTTSOTYcjRxrSwn1ZO71rnF1uSHLAIphz/xxKCkd8G3+hNT8SGwRoujsWj9UxgQR6AjhqpdabQ/ZlaikP2ItnhtSQCtteSAkSo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745238163; c=relaxed/simple; bh=QjppL2LagWrgJRozlKOrpRGPgg5al4nW/gaRNCsK4gQ=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=E7Shp1Qm50zEQgTohalHahauUQ+vWMVAbT/CbQKaJ8afjw8Oe+K0d0Ti4XNvGxowkS3fUkhh+BegoDbW+hfsVz/P6R6YPx+30z+uGjUxbDOse/wv2PxUZb1vrrRmsM2UHqRHq5kIiZbYDamHCywQ/JxSwlVgKKslNh8104ASYHk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dLGr8qkn; 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="dLGr8qkn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E6C0C4CEE4; Mon, 21 Apr 2025 12:22:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745238162; bh=QjppL2LagWrgJRozlKOrpRGPgg5al4nW/gaRNCsK4gQ=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=dLGr8qknCzPJwycOyzeG9tSjiqd4JuVlYDdbTwUXp3lzs9iOJIcobAiz+DnM9/QBK 8zZ6W2j5oCbEXjQhwIMcbyNz4XIdfAyTRd9/6QGSilsXvygEewJ6bfAmg6tlQw+8sd grvBjIWuC9nhd3TCV2ApXkvxPz8j4wpKOCZhWwRsB4zSbqV4WHAUSS2pvVpEQXwFp1 TASMAZVpAeTxab8JvcgjhASFG0ECNLfvLK9LerLfELJiNOoUGOsHOkaDx1RzoJSObK jI0FdwSLvwpEvknM92nF65qeFkXyPM6Q/koPbZoUOMoqWpqBU2RySPHr2MuMtj2qjB GYn7ATTKJonhg== Message-ID: <4f3228ee1730142246c23fd694128488157a9fa7.camel@kernel.org> Subject: Re: [PATCH v2 04/10] sunrpc: Replace the rq_vec 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: Mon, 21 Apr 2025 08:22:40 -0400 In-Reply-To: <20250419172818.6945-5-cel@kernel.org> References: <20250419172818.6945-1-cel@kernel.org> <20250419172818.6945-5-cel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Sat, 2025-04-19 at 13:28 -0400, cel@kernel.org wrote: > From: Chuck Lever >=20 > As a step towards making NFSD's maximum rsize and wsize variable at > run-time, replace the fixed-size rq_vec[] array in struct svc_rqst > with a chunk of dynamically-allocated memory. >=20 > The rq_vec array is sized assuming request processing will need at > most one kvec per page in a maximum-sized RPC message. >=20 > On a system with 8-byte pointers and 4KB pages, pahole reports that > the rq_vec[] array is 4144 bytes. Replacing it with a single > pointer reduces the size of struct svc_rqst to about 5400 bytes. nit: so I guess the current struct is ~9k or so? If you're going to post numbers here, they should probably refer to the same thing. I'm lazy -- don't make me do math. >=20 > Signed-off-by: Chuck Lever > --- > fs/nfsd/nfs4proc.c | 1 - > fs/nfsd/vfs.c | 2 +- > include/linux/sunrpc/svc.h | 2 +- > net/sunrpc/svc.c | 8 +++++++- > 4 files changed, 9 insertions(+), 4 deletions(-) >=20 > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c > index b397246dae7b..d1be58b557d1 100644 > --- a/fs/nfsd/nfs4proc.c > +++ b/fs/nfsd/nfs4proc.c > @@ -1228,7 +1228,6 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_co= mpound_state *cstate, > write->wr_how_written =3D write->wr_stable_how; > =20 > nvecs =3D svc_fill_write_vector(rqstp, &write->wr_payload); > - WARN_ON_ONCE(nvecs > ARRAY_SIZE(rqstp->rq_vec)); > =20 > status =3D nfsd_vfs_write(rqstp, &cstate->current_fh, nf, > write->wr_offset, rqstp->rq_vec, nvecs, &cnt, > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > index 9abdc4b75813..4eaac3aa7e15 100644 > --- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -1094,7 +1094,7 @@ __be32 nfsd_iter_read(struct svc_rqst *rqstp, struc= t svc_fh *fhp, > ++v; > base =3D 0; > } > - WARN_ON_ONCE(v > ARRAY_SIZE(rqstp->rq_vec)); > + WARN_ON_ONCE(v > rqstp->rq_maxpages); > =20 > trace_nfsd_read_vector(rqstp, fhp, offset, *count); > iov_iter_kvec(&iter, ITER_DEST, rqstp->rq_vec, v, *count); > diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h > index 96ac12dbb04d..72d016772711 100644 > --- a/include/linux/sunrpc/svc.h > +++ b/include/linux/sunrpc/svc.h > @@ -207,7 +207,7 @@ struct svc_rqst { > struct page * *rq_page_end; /* one past the last page */ > =20 > struct folio_batch rq_fbatch; > - struct kvec rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */ > + struct kvec *rq_vec; > struct bio_vec rq_bvec[RPCSVC_MAXPAGES]; > =20 > __be32 rq_xid; /* transmission id */ > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > index 682e11c9be36..5808d4b97547 100644 > --- a/net/sunrpc/svc.c > +++ b/net/sunrpc/svc.c > @@ -675,6 +675,7 @@ static void > svc_rqst_free(struct svc_rqst *rqstp) > { > folio_batch_release(&rqstp->rq_fbatch); > + kfree(rqstp->rq_vec); > svc_release_buffer(rqstp); > if (rqstp->rq_scratch_page) > put_page(rqstp->rq_scratch_page); > @@ -713,6 +714,11 @@ svc_prepare_thread(struct svc_serv *serv, struct svc= _pool *pool, int node) > if (!svc_init_buffer(rqstp, serv, node)) > goto out_enomem; > =20 > + rqstp->rq_vec =3D kcalloc_node(rqstp->rq_maxpages, sizeof(struct kvec), > + GFP_KERNEL, node); > + if (!rqstp->rq_vec) > + goto out_enomem; > + > rqstp->rq_err =3D -EAGAIN; /* No error yet */ > =20 > serv->sv_nrthreads +=3D 1; > @@ -1750,7 +1756,7 @@ unsigned int svc_fill_write_vector(struct svc_rqst = *rqstp, > ++pages; > } > =20 > - WARN_ON_ONCE(i > ARRAY_SIZE(rqstp->rq_vec)); > + WARN_ON_ONCE(i > rqstp->rq_maxpages); > return i; > } > EXPORT_SYMBOL_GPL(svc_fill_write_vector); --=20 Jeff Layton