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 D22A72309AE; Tue, 12 Nov 2024 10:40:28 +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=1731408028; cv=none; b=i7Bnz8PVqciBi3rNkWPfrmLh8674iBsQz6GUilqH+HjGAzTkvJqsZGVd+oE3iqCyKtSS7li7vD+Jv6f2JLRffoKHy2XlXEhWgbFN0raYuSpPG7l/DWPOvHzQwieulUFp2kR0WgR/aXHf+XSNGd1L629yRPnnKlL7Iu3ggEPVwaY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731408028; c=relaxed/simple; bh=kymSvZ1E6ys6qq3IaiJ+K+vjzdYvLTXigJrQIwO5n70=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DCp01CHpKsGEppPW3bCrT+SWOrm18swv5RvV785injy54SBIP3ssJ8MyZPfsrOrfPI9O09g362FTzYwYWDnK8MsgAA75Ig0H6aCaq+pbhwvm6x8B3AaBL3KoZdNKNHB9DF4hDyyRZhAZ4mw0XhhBGWKd1i/wBLclC7uI3PxItuA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h21KjhvI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="h21KjhvI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34FAEC4CECD; Tue, 12 Nov 2024 10:40:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1731408028; bh=kymSvZ1E6ys6qq3IaiJ+K+vjzdYvLTXigJrQIwO5n70=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h21KjhvIJfwEgctLFbFv4Uv6HKX8pV/de27XLvphnNOCcG5wNwBUeYxDoLeLmpzcQ An/7COFGW4l67mHAYuYEpddLIRTHFDbwFPjiEJsHAuPc35M4CnHLt50MASYGiuSxcR ONPDKB/BPzpQ5qAH2Z+NNx7fv7774VluH9hZjHso= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mike Snitzer , Jeff Layton , Anna Schumaker , Sasha Levin Subject: [PATCH 6.11 038/184] nfs: avoid i_lock contention in nfs_clear_invalid_mapping Date: Tue, 12 Nov 2024 11:19:56 +0100 Message-ID: <20241112101902.328623277@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241112101900.865487674@linuxfoundation.org> References: <20241112101900.865487674@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Snitzer [ Upstream commit 867da60d463bb2a3e28c9235c487e56e96cffa00 ] Multi-threaded buffered reads to the same file exposed significant inode spinlock contention in nfs_clear_invalid_mapping(). Eliminate this spinlock contention by checking flags without locking, instead using smp_rmb and smp_load_acquire accordingly, but then take spinlock and double-check these inode flags. Also refactor nfs_set_cache_invalid() slightly to use smp_store_release() to pair with nfs_clear_invalid_mapping()'s smp_load_acquire(). While this fix is beneficial for all multi-threaded buffered reads issued by an NFS client, this issue was identified in the context of surprisingly low LOCALIO performance with 4K multi-threaded buffered read IO. This fix dramatically speeds up LOCALIO performance: before: read: IOPS=1583k, BW=6182MiB/s (6482MB/s)(121GiB/20002msec) after: read: IOPS=3046k, BW=11.6GiB/s (12.5GB/s)(232GiB/20001msec) Fixes: 17dfeb911339 ("NFS: Fix races in nfs_revalidate_mapping") Signed-off-by: Mike Snitzer Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin --- fs/nfs/inode.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index b6519f4b12663..e36f3efb3bbc8 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -205,12 +205,15 @@ void nfs_set_cache_invalid(struct inode *inode, unsigned long flags) nfs_fscache_invalidate(inode, 0); flags &= ~NFS_INO_REVAL_FORCED; - nfsi->cache_validity |= flags; + flags |= nfsi->cache_validity; + if (inode->i_mapping->nrpages == 0) + flags &= ~NFS_INO_INVALID_DATA; - if (inode->i_mapping->nrpages == 0) { - nfsi->cache_validity &= ~NFS_INO_INVALID_DATA; - nfs_ooo_clear(nfsi); - } else if (nfsi->cache_validity & NFS_INO_INVALID_DATA) { + /* pairs with nfs_clear_invalid_mapping()'s smp_load_acquire() */ + smp_store_release(&nfsi->cache_validity, flags); + + if (inode->i_mapping->nrpages == 0 || + nfsi->cache_validity & NFS_INO_INVALID_DATA) { nfs_ooo_clear(nfsi); } trace_nfs_set_cache_invalid(inode, 0); @@ -1421,6 +1424,13 @@ int nfs_clear_invalid_mapping(struct address_space *mapping) TASK_KILLABLE|TASK_FREEZABLE_UNSAFE); if (ret) goto out; + smp_rmb(); /* pairs with smp_wmb() below */ + if (test_bit(NFS_INO_INVALIDATING, bitlock)) + continue; + /* pairs with nfs_set_cache_invalid()'s smp_store_release() */ + if (!(smp_load_acquire(&nfsi->cache_validity) & NFS_INO_INVALID_DATA)) + goto out; + /* Slow-path that double-checks with spinlock held */ spin_lock(&inode->i_lock); if (test_bit(NFS_INO_INVALIDATING, bitlock)) { spin_unlock(&inode->i_lock); -- 2.43.0