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[76.133.131.165]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1ff5905b3f3sm127324945ad.136.2024.08.08.11.21.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Aug 2024 11:21:51 -0700 (PDT) Message-ID: <66b50cbf.170a0220.295f9d.891b@mx.google.com> X-Google-Original-Message-ID: Date: Thu, 8 Aug 2024 11:21:50 -0700 From: Vishal Moola To: Alex Shi Cc: alexs@kernel.org, Vitaly Wool , Miaohe Lin , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, minchan@kernel.org, willy@infradead.org, senozhatsky@chromium.org, david@redhat.com, 42.hyeyoo@gmail.com, Yosry Ahmed , nphamcs@gmail.com Subject: Re: [PATCH v4 01/22] mm/zsmalloc: add zpdesc memory descriptor for zswap.zpool References: <20240729112534.3416707-1-alexs@kernel.org> <20240729112534.3416707-2-alexs@kernel.org> <66ad2ad7.170a0220.3a8e93.6a32@mx.google.com> 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: 8840A40019 X-Stat-Signature: gyaawk9g915a51auuygn9se364cuuafb X-Rspam-User: X-HE-Tag: 1723141313-924677 X-HE-Meta: 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 GpiXTICN 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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 Mon, Aug 05, 2024 at 12:06:24PM +0800, Alex Shi wrote: > > > On 8/3/24 2:52 AM, Vishal Moola wrote: > > On Mon, Jul 29, 2024 at 07:25:13PM +0800, alexs@kernel.org wrote: > >> From: Alex Shi > > > >> + static_assert(offsetof(struct page, pg) == offsetof(struct zpdesc, zp)) > >> + > >> +ZPDESC_MATCH(flags, flags); > >> +ZPDESC_MATCH(lru, lru); > >> +ZPDESC_MATCH(mapping, mops); > >> +ZPDESC_MATCH(index, next); > >> +ZPDESC_MATCH(index, handle); > >> +ZPDESC_MATCH(private, zspage); > >> +#ifdef CONFIG_MEMCG > >> +ZPDESC_MATCH(memcg_data, memcg_data); > >> +#endif > >> +#undef ZPDESC_MATCH > >> +static_assert(sizeof(struct zpdesc) <= sizeof(struct page)); > >> + > >> +#define zpdesc_page(zp) (_Generic((zp), \ > >> + const struct zpdesc *: (const struct page *)(zp), \ > >> + struct zpdesc *: (struct page *)(zp))) > >> + > >> +#define zpdesc_folio(zp) (_Generic((zp), \ > >> + const struct zpdesc *: (const struct folio *)(zp), \ > >> + struct zpdesc *: (struct folio *)(zp))) > >> + > >> +#define page_zpdesc(p) (_Generic((p), \ > >> + const struct page *: (const struct zpdesc *)(p), \ > >> + struct page *: (struct zpdesc *)(p))) > >> + > >> +#endif > > > > I'm don't think we need both page and folio cast functions for zpdescs. > > Sticking to pages will probably suffice (and be easiest) since all APIs > > zsmalloc cares about are already defined. > > > > We can stick to 1 "middle-man" descriptor for zpdescs since zsmalloc > > uses those pages as space to track zspages and nothing more. We'll likely > > end up completely removing it from zsmalloc once we can allocate > > memdescs on their own: It seems most (if not all) of the "indirect" members > > of zpdesc are used as indicators to the rest of core-mm telling them not to > > mess with that memory. > > Yes, that is also my first attempt to skip folio part, but I found we could got > 6.3% object size reduced on zsmalloc.o file, from 37.2KB to 34.9KB, if we use > folio series lock and folio_get/put functions. That saving come from compound_head > check skipping. > So I wrapped them carefully in zpdesc series functions in zpdesc.h file. > They should be easy replaced when we use memdescs in the future. Could we keep them > a while, or ? IMO, Its alright to keep both pages and folios due to the size reduction. However if we do keep both, it should be clearer that we Want zpdescs to be order-0 pages, and the only reason we have folios is that compound_head() size reduction (and nothing more). I think a comment by the zpdesc_folio() macro will suffice. > Thanks > Alex >