From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 18A0A43152; Wed, 4 Sep 2024 04:29:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725424175; cv=none; b=LMIpGYeyUdiDBnBQniLo692FQvBPEr0R7+9nEmu/lUyjvx1jJHRSc26QxTJRcIIYqlCQeYG4rS7GbSfP397Kmk75L7qNkpwJJBzjMrvgzvvozOpepsl0N43I/US9mc6b9KKEzMo0lN2F6hRdi0cTk+QhOT7GAT0lpzz2zuZihBE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725424175; c=relaxed/simple; bh=Y8IXN1rN2RoNHDeeGDPC4uyggAqYskHFl46L+lSWZZM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SHHmXlg10m387s7pCbumR/7AWGUDJJaMbSd/1MeZHynIn16SM4SaIfP6nULlz88sD6s8UEDGJ4s1NwtrUfnM2zpJKm6bM29PpjTHdbQettXhKqGOE/BrOWsIWN7jJo2SPVRAgH+UjpYOqiVGHA6NsMS9tw1rbFg4MqBBwB7bsmo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=Xfldbzlh; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Xfldbzlh" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=BBc8Ka/vR8SFvHYVTELQXwp9sVABJ6GRH/edBy/xYJw=; b=XfldbzlhVwTQcy2y56lbSO/SZ2 ku/6kecuHVgT33L6kVM8CaNM7t62Ycsq1Q+tbQkYjmTZ9OBqPDecadEcLHmrrZ+Hehosl2XFG8kZ0 eYhE+axQCaqiwy8oiJbDwvtt1iuDQjKMJ8Zc8ip+fh/0elRzFgSdsidDSlgDK1+7VypWjeQoyeGf1 IrNSlgNatfzHyCOldQwpOuotpheeIy66hO0tYtsNrLu+J+Y4CLhCkZyhyBFI0oDmlWw3Njom/Z3Jv nx+ZHwWJCZe3gKx09dG6cG4+SNgfu9OXFN1IQ97rPdCrGPQ3NSX3VCzYpHJfcY/fqlNu0Mfqfpvzz cI2455gA==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1slhe7-00000002nJS-3YSH; Wed, 04 Sep 2024 04:29:31 +0000 Date: Tue, 3 Sep 2024 21:29:31 -0700 From: Christoph Hellwig To: Jens Axboe Cc: ZhangHui , bvanassche@acm.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] block: move non sync requests complete flow to softirq Message-ID: References: <20240903115437.42307-1-zhanghui31@xiaomi.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Sep 03, 2024 at 11:49:28AM -0600, Jens Axboe wrote: > The elephant in the room here is why an 80M completion takes 100 msec? > That seems... insane. > > That aside, doing writes that big isn't great for latencies in general, > even if they are orders of magnitude smaller (as they should be). Maybe > this is solvable by just limiting the write size here. > > But it really seems out of line for a write that size to take 100 msec > to process. pagecache state processing is quite inefficient, we had to limit the number of them for XFS to avoid latency problems a while ago. Note that moving to folios means you can process a lot more data with the same number of completion iterations as well. I'd suggest the submitter looks into that for whatever file system they are using.