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 8546AD26D for ; Sat, 15 Jun 2024 02:59:22 +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=1718420362; cv=none; b=th4iHccpRZk/COdbxFbOGeGYYeD6Snm/dlX6HvV4ST/LVzNC8pg37R+gNK6mJnRfPrHwb1vb0pC+mWfQowuQO/cwVnGXCO/goX8jedr1ecYbmPwKfrYHimNcKJajJsencFREUOtgqCrxIbSsMjN8NJTy6rL3sNeSqE64gCVoY0E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718420362; c=relaxed/simple; bh=mkjvUJdS5vqjmt9WAxPq2GEHmcIbM2iUAlz3+HnWaMY=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=meDiHebTnGjPzPAF9St/8lQChhigDSw52VUNd7tFpl60NHPcTvqb1MxAVS45VTCfV7ldbQLyu5K0hoWRll0bZtyuXPJPfguqge8cmX8m8PVZchIKX/LRRVSa0PvrWuCK9rikLJLNsuP5MZnCwfOJUxWaNX3ZZQ4AAxl4Qbu6ZUU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=hx7Duybr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="hx7Duybr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0AD4C2BD10; Sat, 15 Jun 2024 02:59:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1718420362; bh=mkjvUJdS5vqjmt9WAxPq2GEHmcIbM2iUAlz3+HnWaMY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=hx7Duybr78IeEsr/EImsxu6uIAwwA+fZXVTBNX+bBzb8Q2ioN/qZ9CLLDLhVYy14b 206BpUY4e94wgEIV7RPj5R7hhMB5+kIvC/h7akfAYKg0lpbAR5yqTvAqlkKDbYyiwz +xq/GFmEmVU5K7t5GoxPq2YcHdlYz7gDfH19fAlM= Date: Fri, 14 Jun 2024 19:59:21 -0700 From: Andrew Morton To: Chris Li Cc: Kairui Song , Ryan Roberts , "Huang, Ying" , Kalesh Singh , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Barry Song Subject: Re: [PATCH v2 0/2] mm: swap: mTHP swap allocator base on swap cluster order Message-Id: <20240614195921.a20f1766a78b27339a2a3128@linux-foundation.org> In-Reply-To: References: <20240614-swap-allocator-v2-0-2a513b4a7f2f@kernel.org> <20240614180606.5f3b6f4a6cd515df30b7a0e4@linux-foundation.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 14 Jun 2024 19:51:11 -0700 Chris Li wrote: > > I'm having trouble understanding the overall impact of this on users. > > We fail the mTHP swap allocation and fall back, but things continue to > > operate OK? > > Continue to operate OK in the sense that the mTHP will have to split > into 4K pages before the swap out, aka the fall back. The swap out and > swap in can continue to work as 4K pages, not as the mTHP. Due to the > fallback, the mTHP based zsmalloc compression with 64K buffer will not > happen. That is the effect of the fallback. But mTHP swap out and swap > in is relatively new, it is not really a regression. Sure, but it's pretty bad to merge a new feature only to have it ineffective after a few hours use. > > > > > There is some test number in the V1 thread of this series: > > > https://lore.kernel.org/r/20240524-swap-allocator-v1-0-47861b423b26@kernel.org > > > > Well, please let's get the latest numbers into the latest patchset. > > Along with a higher-level (and quantitative) description of the user impact. > > I will need Barray's help to collect the number. I don't have the > setup to reproduce his test result. > Maybe a follow up commit message amendment for the test number when I get it? Yep, I alter changelogs all the time. > > > > I'll add this into mm-unstable now for some exposure, but at this point > > I'm not able to determine whether it should go in as a hotfix for > > 6.10-rcX. > > Maybe not need to be a hotfix. Not all Barry's mTHP swap out and swap > in patch got merged yet. OK, well please let's give appropriate consideration to what we should add to 6.10-rcX in order to have this feature working well.