From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 90AF4D6552C for ; Wed, 17 Dec 2025 12:02:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E974C6B0005; Wed, 17 Dec 2025 07:02:36 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E657C6B0089; Wed, 17 Dec 2025 07:02:36 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D711D6B008A; Wed, 17 Dec 2025 07:02:36 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id C40936B0005 for ; Wed, 17 Dec 2025 07:02:36 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 5494A140A5E for ; Wed, 17 Dec 2025 12:02:36 +0000 (UTC) X-FDA: 84228825912.14.DFF696C Received: from mail-lf1-f54.google.com (mail-lf1-f54.google.com [209.85.167.54]) by imf21.hostedemail.com (Postfix) with ESMTP id 548A91C0013 for ; Wed, 17 Dec 2025 12:02:34 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=XKnAwzNO; spf=pass (imf21.hostedemail.com: domain of urezki@gmail.com designates 209.85.167.54 as permitted sender) smtp.mailfrom=urezki@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1765972954; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=OJt3OeOAET42H1SZeq/73bRk3HyaCcKWTnzPipXTmdU=; b=qdLAEIa+O9h4wjG4Io9aX3FMTi2LF9Eih7cNLheZfiFYcZVqQGhoI44s6a+nLyLYCSe4vX G1OHlZCujOIfbaEQO5Xc9kprlv8Fj6Ih3G+xGVQ6KptkfHXAQ+fcSMauqnKpXrPN+nOHsq fHBN+x+UptLW3w4c4WfQpfAgt2PKoVI= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=XKnAwzNO; spf=pass (imf21.hostedemail.com: domain of urezki@gmail.com designates 209.85.167.54 as permitted sender) smtp.mailfrom=urezki@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1765972954; a=rsa-sha256; cv=none; b=u27ovuwSEX91ocb8IhINvWHa/fllni6g33BkbNTpu85euWRyAzC0EL+7AEoLYAKKEx+/N4 /kRdXy9YgAvoggrGXhrDELs6dYYJ8bbM+g+cu9WAqvOv0ulVz3CtpWN7yL5JTu8Zh8EaFY YBi98YbGxfsZ7uFlY7IJK73nfW1tihU= Received: by mail-lf1-f54.google.com with SMTP id 2adb3069b0e04-596ba05aaecso6441257e87.0 for ; Wed, 17 Dec 2025 04:02:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1765972952; x=1766577752; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=OJt3OeOAET42H1SZeq/73bRk3HyaCcKWTnzPipXTmdU=; b=XKnAwzNOO+LyOmZjLONdUcy5CLaOFIS/OH3gRRDUeyeUnP8fi6x5fOloc4v7AoCz7P Y7Z6S1uywclaXaMkArCrE3wAkP1SVIsl52x8kLM2I4LN5YinxwkESlH3QIiqf+nhudHH qs7j8CyMY34Yz6yHS9KjKi3hUik014a0yf8+6aL6vfaJARN4vhHDigCh1eJmtRJkA4Zz bL5TASI0dKJo3O/dC9Lh5hOsfTBeJUGxTTk6A17f4mcKIz2fwbXDp5Snpi5DrkCjEYhz FRYZsBtLeOJXoOYyXtN7Ltz1tlkA3uc154kMohffAeUA30ek9M32RhFFHm6suld1vInM O2jg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765972952; x=1766577752; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=OJt3OeOAET42H1SZeq/73bRk3HyaCcKWTnzPipXTmdU=; b=QRUluVvc8QFnpd8e7cfulGt2CP/L9OPPL16MPkw/oMqVd2kxcKJG+HnH2EGP4CYpaR OGK5IRzHQHZXQH3awwKApUDJ5P0mcqTuYN2joqZd/jIFKcRQUV1ney1jIdW7UEQc06iV B5s1dXr8xbE4tifujn+5miM2n+4JT8RUAo8hzZqNZfjcLpd+ZZY00ZqvH4PSAU/tfI1o LbA6mzwkpm60cyFZc7voBVRJyMKu8E0pkR/8pA+OLfmP9QiNgDOsvd94WQUiRbSWGb7/ nbRkNCaErBbUNR3guH9uNkcqVuv2boQe5hnDtYdStGnOAZyfWP+ZHRMXWog4I4LhBZvW SRXg== X-Forwarded-Encrypted: i=1; AJvYcCX4VAOBF4xvOEMEMmId6mKXnNJOZg5A6moY38zrSeKDw6E6vpM3NhcdHdmxoooGjIRzTlaEaLAIKQ==@kvack.org X-Gm-Message-State: AOJu0YzrSmygouUPQL5ZaNCDSc1A0fZIm05mLNglifP8Dn2Ucza6s+DO YkMi7VQrJszjadtnWrxdWrRhwNHS/hnPp1k1IuzzzDWi8gcvY8qs8hvlZJ18ffUv X-Gm-Gg: AY/fxX5Vlq7SYavuiemEEqlxutmpyQHQbgfk7XbihdClCLMYTDbdeRxcOH9wgdctbew w+NNgVGclTvWvRW6Lpaiux+ancATp7uGOgZzKM/q0fGqLH9EMEohK/mckk+ARrgK3y74kMsvW+h KxsHlogkAdTQS6f7CzGd0HByHK8GDhzpU3VurXkcdRPOWsJBS3SjQXnvC6ECEdjoO/x+ENSK6QK lDHvT6x3g0g23Thr3txuuy9S8lXBkGpcTOVhvoGu4NOAl02Ur+LKkMAinwXjfIyRU3q2Vr7+UiA n/LHsBSQO+nh46VDrI10Nn0nE5/AE6rkKwtYMSlsu+i/WP9/Et7h8/d5zpGqq8OS9WjcpGnPDMJ N/ApdyAlwPSEb6imDI4Af7FATB1Hf7z4GpYOJjy855226fIaNDqzzNZZ/Ijw1U9s= X-Google-Smtp-Source: AGHT+IEvC8B8oWcr0SIWQAYhh3wI3svFk5jPcenoh+vUpS22lTjVeH41fkW0PDI4QJj3OoDOzFAiww== X-Received: by 2002:a05:6512:3f2a:b0:595:8311:dc80 with SMTP id 2adb3069b0e04-598faa27bd9mr5964892e87.20.1765972952322; Wed, 17 Dec 2025 04:02:32 -0800 (PST) Received: from milan ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5990da5dcdcsm2312647e87.73.2025.12.17.04.02.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 04:02:31 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Wed, 17 Dec 2025 13:02:29 +0100 To: Ryan Roberts Cc: "Uladzislau Rezki (Sony)" , linux-mm@kvack.org, Andrew Morton , Vishal Moola , Dev Jain , Baoquan He , LKML Subject: Re: [PATCH 2/2] mm/vmalloc: Add attempt_larger_order_alloc parameter Message-ID: References: <20251216211921.1401147-1-urezki@gmail.com> <20251216211921.1401147-2-urezki@gmail.com> <6ca6e796-cded-4221-b1f8-92176a80513e@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6ca6e796-cded-4221-b1f8-92176a80513e@arm.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 548A91C0013 X-Stat-Signature: 94jjkz5oif83ikgnwdtdzqfypak85bc9 X-Rspam-User: X-HE-Tag: 1765972954-773640 X-HE-Meta: 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 LMEn0FyC 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On 16/12/2025 21:19, Uladzislau Rezki (Sony) wrote: > > Introduce a module parameter to enable or disable the large-order > > allocation path in vmalloc. High-order allocations are disabled by > > default so far, but users may explicitly enable them at runtime if > > desired. > > > > High-order pages allocated for vmalloc are immediately split into > > order-0 pages and later freed as order-0, which means they do not > > feed the per-CPU page caches. As a result, high-order attempts tend > > to bypass the PCP fastpath and fall back to the buddy allocator that > > can affect performance. > > > > However, when the PCP caches are empty, high-order allocations may > > show better performance characteristics especially for larger > > allocation requests. > > I wonder if a better solution would be "allocate order-0 if available in pcp, > else try large order, else fallback to order-0" Could that provide the best of > all worlds without needing a configuration knob? > I am not sure, to me it looks like a bit odd. Ideally it would be good just free it as high-order page and not order-0 peaces. > > > > Since the best strategy is workload-dependent, this patch adds a > > parameter letting users to choose whether vmalloc should try > > high-order allocations or stay strictly on the order-0 fastpath. > > > > Signed-off-by: Uladzislau Rezki (Sony) > > --- > > mm/vmalloc.c | 9 +++++++-- > > 1 file changed, 7 insertions(+), 2 deletions(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index d3a4725e15ca..f66543896b16 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -43,6 +43,7 @@ > > #include > > #include > > #include > > +#include > > > > #define CREATE_TRACE_POINTS > > #include > > @@ -3671,6 +3672,9 @@ vm_area_alloc_pages_large_order(gfp_t gfp, int nid, unsigned int order, > > return nr_allocated; > > } > > > > +static int attempt_larger_order_alloc; > > +module_param(attempt_larger_order_alloc, int, 0644); > > Would this be better as a bool? Docs say that you can then specify 0/1, y/n or > Y/N as the value; that's probably more intuitive? > > nit: I'd favour a shorter name. Perhaps large_order_alloc? > Thanks! We can switch to bool and use shorter name for sure. -- Uladzislau Rezki