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Howlett" , Vlastimil Babka , Michal Hocko Cc: Suren Baghdasaryan , Suleiman Souhlal , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: Re: mm: swapin read-ahead and zram Message-ID: References: <7ftwasufn2w3bgesfbp66vlchhpiuctxkhdxp24y5nzzgz2oip@pi4kdyqkl5ss> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7ftwasufn2w3bgesfbp66vlchhpiuctxkhdxp24y5nzzgz2oip@pi4kdyqkl5ss> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 7E6E240002 X-Stat-Signature: trqyici5tpf7fptgxstf3j7xfgot1wbj X-Rspam-User: X-HE-Tag: 1755238857-848068 X-HE-Meta: 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 B5ACWzHD DswHk/KwHyssFeimfgici51uwqOYfGNBL8s0rpsDx1TfTlbkdJ/iXuRhX4E0CNxNl13+V/6B0swtC11fwyvrK/XOsiZVNAKNQcll4YGi/exc5AacvWL9L/eoZwgMb02T4A0YhKKH5sgPU+hCMrhG5S5su/ZY/be+sZYhhpXKwthm0/p+Zhsk1G/Aj+2oWqlAy+/vaReSeq1r6K77r0JquGj9TxOZ4c+0hEfIcr/dxikuGuE1niKW+BlFbw+l4CH7UfoJR9xNgH17ZIkjyjkB4N0QDdY6yrPKmV9+Nzd/rxziy9FwwsgqRbCihz+P+1k85Y/wB4j2/BUmLh9CnxXi1cisYHX9ghkZEDrz19wff8uHGZ3Y= 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 (25/08/15 14:51), Sergey Senozhatsky wrote: [..] > For instance, notice how entry 1615265 is read, decompressed, then > presumably evicted from the memory, and read/decompressed again > soon after, almost immediately. Also notice how that entry 1615265 > has already went through this cycle 189 times. It's not entirely > clear why this happens. > > As far as I can tell, it seems that these extra zram reads are coming from > the swapin read-ahead: > handle_mm_fault > do_swap_page > swapin_readahead > swap_read_folio > submit_bio_wait > submit_bio_noacct_nocheck > __submit_bio > zram_submit_bio > zram_read_page > zram_read_from_zspool Sorry, I need to correct myself here, it seems that read-ahead win is 1 pretty much all the time in swap_vma_readahead(), so that's probably not read-ahead after all.