Hello Andrew, On 2015-11-24 오전 7:52, Andrew Morton wrote: > On Mon, 23 Nov 2015 15:21:15 +0900 Kyeongdon Kim <kyeongdon....@lge.com> > wrote: > >> When we're using LZ4 multi compression streams for zram swap, >> we found out page allocation failure message in system running test. >> That was not only once, but a few(2 - 5 times per test). >> Also, some failure cases were continually occurring to try allocation >> order 3. >> >> In order to make parallel compression private data, we should call >> kzalloc() with order 2/3 in runtime(lzo/lz4). But if there is no order >> 2/3 size memory to allocate in that time, page allocation fails. >> This patch makes to use vmalloc() as fallback of kmalloc(), this >> prevents page alloc failure warning. >> >> After using this, we never found warning message in running test, also >> It could reduce process startup latency about 60-120ms in each case. >> >> ... >> >> --- a/drivers/block/zram/zcomp_lz4.c >> +++ b/drivers/block/zram/zcomp_lz4.c >> @@ -10,17 +10,25 @@ >> #include <linux/kernel.h> >> #include <linux/slab.h> >> #include <linux/lz4.h> >> +#include <linux/vmalloc.h> >> +#include <linux/mm.h> >> >> #include "zcomp_lz4.h" >> >> static void *zcomp_lz4_create(void) >> { >> - return kzalloc(LZ4_MEM_COMPRESS, GFP_KERNEL); >> + void *ret; >> + >> + ret = kzalloc(LZ4_MEM_COMPRESS, >> + __GFP_NORETRY|__GFP_NOWARN|__GFP_NOMEMALLOC); >> + if (!ret) >> + ret = vzalloc(LZ4_MEM_COMPRESS); >> + return ret; >> } > > What's the reasoning behind the modification to the gfp flags? > > It clears __GFP_FS, __GFP_IO and even __GFP_WAIT. I suspect the latter > two (at least) can be retained. And given that vmalloc() uses > GFP_KERNEL, what's the point in clearing those flags for the kmalloc() > case? > > If this change (or something like it) remains in place, it should have > a comment which fully explains the reasons, please.
Sorry for the delay in replying, I just tried to remove that warning message. If there are more rightable gfp flags(like a code in Minchan's patch), we can use it. Thanks, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/