From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0098C20B1EE; Wed, 16 Oct 2024 15:09:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729091367; cv=none; b=kkqDR5cKdQrKvo9Ar3e7+tkOZHk/pkFfo9+okXJHCDlRIl9e9Ij0eupqMmHokmPkqaWaQWPJxNlMPHTw937Zc1MMKR5quVEqcCvH1t8HO7ymx0FyBwgF6isJwrDyJYhhCxqvEZxlcgk8dW/WZZmYX016MjosU+Y8EJUjrU4Pvic= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729091367; c=relaxed/simple; bh=gRPb5P1k9UfY8ZGiYWYsNqS7y22Jny7V3mVzeUcEEe8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=i5GhRh/SN59ycN8pRuR1Djwk6Jp59TrZMuMZweCuBIhXRwFd/dNWg48tjWJxfyHPrpElopY+gYzAOtBzSnOz2GwwksUuyj1eYwAEAJoW9R6jB2Jy6HuOovJlFjpt6u4SXQ1A7G9unsaxt96ZCQ4MHEOhWym7aU5LiCf6gKORL3o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F1651FEC; Wed, 16 Oct 2024 08:09:53 -0700 (PDT) Received: from [10.1.28.177] (XHFQ2J9959.cambridge.arm.com [10.1.28.177]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0C8003F528; Wed, 16 Oct 2024 08:09:20 -0700 (PDT) Message-ID: Date: Wed, 16 Oct 2024 16:09:19 +0100 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 21/57] sunrpc: Remove PAGE_SIZE compile-time constant assumption Content-Language: en-GB To: Jeff Layton , Chuck Lever Cc: Andrew Morton , Anna Schumaker , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Greg Marsden , Ivan Ivanov , Kalesh Singh , Marc Zyngier , Mark Rutland , Matthias Brugger , Miroslav Benes , Trond Myklebust , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org References: <20241014105514.3206191-1-ryan.roberts@arm.com> <20241014105912.3207374-1-ryan.roberts@arm.com> <20241014105912.3207374-21-ryan.roberts@arm.com> <33a6cc271475b0fc520b8fc20ed0b4f7742a2560.camel@kernel.org> From: Ryan Roberts In-Reply-To: <33a6cc271475b0fc520b8fc20ed0b4f7742a2560.camel@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 16/10/2024 15:54, Jeff Layton wrote: > On Wed, 2024-10-16 at 10:47 -0400, Chuck Lever wrote: >> On Wed, Oct 16, 2024 at 03:42:12PM +0100, Ryan Roberts wrote: >>> + Chuck Lever, Jeff Layton >>> >>> This was a rather tricky series to get the recipients correct for and my script >>> did not realize that "supporter" was a pseudonym for "maintainer" so you were >>> missed off the original post. Appologies! >>> >>> More context in cover letter: >>> https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/ >>> >>> >>> On 14/10/2024 11:58, Ryan Roberts wrote: >>>> To prepare for supporting boot-time page size selection, refactor code >>>> to remove assumptions about PAGE_SIZE being compile-time constant. Code >>>> intended to be equivalent when compile-time page size is active. >>>> >>>> Updated array sizes in various structs to contain enough entries for the >>>> smallest supported page size. >>>> >>>> Signed-off-by: Ryan Roberts >>>> --- >>>> >>>> ***NOTE*** >>>> Any confused maintainers may want to read the cover note here for context: >>>> https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/ >>>> >>>> include/linux/sunrpc/svc.h | 8 +++++--- >>>> include/linux/sunrpc/svc_rdma.h | 4 ++-- >>>> include/linux/sunrpc/svcsock.h | 2 +- >>>> 3 files changed, 8 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h >>>> index a7d0406b9ef59..dda44018b8f36 100644 >>>> --- a/include/linux/sunrpc/svc.h >>>> +++ b/include/linux/sunrpc/svc.h >>>> @@ -160,6 +160,8 @@ extern u32 svc_max_payload(const struct svc_rqst *rqstp); >>>> */ >>>> #define RPCSVC_MAXPAGES ((RPCSVC_MAXPAYLOAD+PAGE_SIZE-1)/PAGE_SIZE \ >>>> + 2 + 1) >>>> +#define RPCSVC_MAXPAGES_MAX ((RPCSVC_MAXPAYLOAD+PAGE_SIZE_MIN-1)/PAGE_SIZE_MIN \ >>>> + + 2 + 1) >> >> There is already a "MAX" in the name, so adding this new macro seems >> superfluous to me. Can we get away with simply updating the >> "RPCSVC_MAXPAGES" macro, instead of adding this new one? >> > > +1 that was my thinking too. This is mostly just used to size arrays, > so we might as well just change the existing macro. I agree, its not the prettiest. I was (incorrectly) assuming you would want to continue to limit the number of actual pages at runtime based on the in-use page size. That said, looking again at the code, RPCSVC_MAXPAGES never actually gets used to dynamically allocate any memory. So I propose to just do the following: #define RPCSVC_MAXPAGES ((RPCSVC_MAXPAYLOAD+PAGE_SIZE_MIN-1)/ PAGE_SIZE_MIN + 2 + 1) That will be 259 in practice (assuming PAGE_SIZE_MIN=4K). > > With 64k pages we probably wouldn't need arrays as long as these will > be. Fixing those array sizes to be settable at runtime though is not a > trivial project though. Indeed. Hopefully the above is sufficient. Thanks for the review! Ryan > >> >>>> /* >>>> * The context of a single thread, including the request currently being >>>> @@ -190,14 +192,14 @@ struct svc_rqst { >>>> struct xdr_stream rq_res_stream; >>>> struct page *rq_scratch_page; >>>> struct xdr_buf rq_res; >>>> - struct page *rq_pages[RPCSVC_MAXPAGES + 1]; >>>> + struct page *rq_pages[RPCSVC_MAXPAGES_MAX + 1]; >>>> struct page * *rq_respages; /* points into rq_pages */ >>>> struct page * *rq_next_page; /* next reply page to use */ >>>> struct page * *rq_page_end; /* one past the last page */ >>>> >>>> struct folio_batch rq_fbatch; >>>> - struct kvec rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */ >>>> - struct bio_vec rq_bvec[RPCSVC_MAXPAGES]; >>>> + struct kvec rq_vec[RPCSVC_MAXPAGES_MAX]; /* generally useful.. */ >>>> + struct bio_vec rq_bvec[RPCSVC_MAXPAGES_MAX]; >>>> >>>> __be32 rq_xid; /* transmission id */ >>>> u32 rq_prog; /* program number */ >>>> diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h >>>> index d33bab33099ab..7c6441e8d6f7a 100644 >>>> --- a/include/linux/sunrpc/svc_rdma.h >>>> +++ b/include/linux/sunrpc/svc_rdma.h >>>> @@ -200,7 +200,7 @@ struct svc_rdma_recv_ctxt { >>>> struct svc_rdma_pcl rc_reply_pcl; >>>> >>>> unsigned int rc_page_count; >>>> - struct page *rc_pages[RPCSVC_MAXPAGES]; >>>> + struct page *rc_pages[RPCSVC_MAXPAGES_MAX]; >>>> }; >>>> >>>> /* >>>> @@ -242,7 +242,7 @@ struct svc_rdma_send_ctxt { >>>> void *sc_xprt_buf; >>>> int sc_page_count; >>>> int sc_cur_sge_no; >>>> - struct page *sc_pages[RPCSVC_MAXPAGES]; >>>> + struct page *sc_pages[RPCSVC_MAXPAGES_MAX]; >>>> struct ib_sge sc_sges[]; >>>> }; >>>> >>>> diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h >>>> index 7c78ec6356b92..6c6bcc82685a3 100644 >>>> --- a/include/linux/sunrpc/svcsock.h >>>> +++ b/include/linux/sunrpc/svcsock.h >>>> @@ -40,7 +40,7 @@ struct svc_sock { >>>> >>>> struct completion sk_handshake_done; >>>> >>>> - struct page * sk_pages[RPCSVC_MAXPAGES]; /* received data */ >>>> + struct page * sk_pages[RPCSVC_MAXPAGES_MAX]; /* received data */ >>>> }; >>>> >>>> static inline u32 svc_sock_reclen(struct svc_sock *svsk) >>> >> >