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Sun, 11 Jan 2026 21:07:30 -0800 (PST) Received: from google.com ([2a00:79e0:2031:6:e4c9:1271:e310:135]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a3e3cc88fcsm160169225ad.83.2026.01.11.21.07.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 11 Jan 2026 21:07:29 -0800 (PST) Date: Mon, 12 Jan 2026 14:07:24 +0900 From: Sergey Senozhatsky To: Herbert Xu Cc: Yosry Ahmed , Sergey Senozhatsky , Andrew Morton , Nhat Pham , Minchan Kim , Johannes Weiner , Brian Geffon , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 2/2] zsmalloc: chain-length configuration should consider other metrics Message-ID: References: <9b7d6e6292c64f21b8d09def1b6723f02faffe88@linux.dev> <53zplsrqc66z4ea64cosy53zvttuuhgxr2ik7uw6i2zgluegyz@d3ulgntwnyw4> <2iophcy2e6vk72ypxeshmen66e7jhr52zr34parn4uw6vdyjef@frnpfrltrky2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7B1D840009 X-Stat-Signature: n59hwtsnserst565x9f4r3ui6xjdky1q X-Rspam-User: X-HE-Tag: 1768194451-232943 X-HE-Meta: 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 1N9F4C0U 2jWBegZ4wENSIkYWtS+WMFjjkrWNlvVfyIUFUZrKe4tjsAR90t8qAaL+9boa4dTN8K7rBwsXwgtZsTu7ZxrnpprI+UvtQalvMgtSkZ3Sxq8Ay723Vh7O+6V3Yzr6GxYsWwlH/hEwl4Ng3vK75gWBqbmxjtXIIQdtEyCKTQEXSZge7gs6vHfOM9QKOZyAjDuKyzIJiO5VvYchBicImiuo175p03wLOUQOnEBnFGiIF1dE7+3PCLYnOYi5wn2BEuf8z72XnFvP8btytCjvzP0iPTsa6bvcn1Fh4VKrb+nJgNWeiEHls79ly7YssV6ROoDCG9+kystN+rrtFaJR6xVBlK+b0nHT4ve14Y3wvR41jnwpROxY= 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 (26/01/12 13:01), Herbert Xu wrote: > On Fri, Jan 09, 2026 at 04:02:51PM +0000, Yosry Ahmed wrote: > > > > Herbert, do you mind taking a look at this? It looks sane to me except > > for one question below. > > Looks alright to me too. > > > > + size_t sizes[2]; > > > + > > > + /* this object spans two pages */ > > > + sizes[0] = PAGE_SIZE - off; > > > + sizes[1] = mem_len - sizes[0]; > > > + > > > + sg_init_table(sg, 2); > > > + sg_set_page(sg, zpdesc_page(zpdesc), sizes[0], off); > > > + > > > + zpdesc = get_next_zpdesc(zpdesc); > > > + sg = sg_next(sg); > > > > Is this stateful? Will the SG list be returned pointing at the second > > page now? > > It makes no difference because we just called sg_init_table(sg, 2), > so sg_next(sg) is equivalent to &sg[1]. I did it this way for (sort of) consistency: sg next follows zpdesc next.