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Date: Tue, 25 Oct 2022 10:21:02 +0900 From: Sergey Senozhatsky <senozhatsky@...omium.org> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Alexey Romanov <avromanov@...rdevices.ru>, minchan@...nel.org, senozhatsky@...omium.org, ngupta@...are.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, kernel@...rdevices.ru Subject: Re: [PATCH v1] zram: add size class equals check into recompression On (22/10/24 13:59), Andrew Morton wrote: > > It makes no sense for us to recompress the object if it will > > be in the same size class. We anyway don't get any memory gain. > > But, at the same time, we get a CPU time overhead when inserting > > this object into zspage and decompressing it afterwards. > > > > Dumb question: is it ever possible for compression to result in an > increase in size? That's a good question. Re-compressed object can be bigger than the original compressed one, but this should already be taken care of. We do if (comp_len_next >= huge_class_size || comp_len_next >= comp_len_prev || This checks whether recompressed object is above huge-size watermark and whether recompressed size is larger than the original size.
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