> -----Original Message----- > From: Dave Hansen [mailto:dave.hansen@xxxxxxxxx] > Sent: Friday, April 30, 2021 10:39 AM > To: Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx>; tiantao (H) > <tiantao6@xxxxxxxxxxxxx>; corbet@xxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx > Cc: linux-doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Rafael J. > Wysocki <rafael@xxxxxxxxxx>; Peter Zijlstra <peterz@xxxxxxxxxxxxx>; Valentin > Schneider <valentin.schneider@xxxxxxx>; Dave Hansen > <dave.hansen@xxxxxxxxxxxxxxx>; Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> > Subject: Re: [PATCH 1/2] CPU, NUMA topology ABIs: clarify the overflow issue > of sysfs pagebuf > > On 4/29/21 3:32 PM, Song Bao Hua (Barry Song) wrote: > > $ strace numactl --hardware 2>&1 | grep cpu > > openat(AT_FDCWD, "/sys/devices/system/cpu", > > O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 3 > > openat(AT_FDCWD, "/sys/devices/system/node/node0/cpumap", O_RDONLY) = 3 > > openat(AT_FDCWD, "/sys/devices/system/node/node1/cpumap", O_RDONLY) = 3 > > openat(AT_FDCWD, "/sys/devices/system/node/node2/cpumap", O_RDONLY) = 3 > > openat(AT_FDCWD, "/sys/devices/system/node/node3/cpumap", O_RDONLY) = 3 > > > > If we move to binary, it means we have to change those applications. > > I thought Greg was saying to using a sysfs binary attribute using > something like like sysfs_create_bin_file(). Those don't have the > PAGE_SIZE limitation. But, there's also nothing to keep us from spewing > nice human-readable text via the "binary" file. > > We don't need to change the file format, just the internal kernel API > that we produce the files with. Dave, thanks for clarification. Sounds a way to go. Barry
