On Wed, 13 Feb 2019 09:31:03 -0800 Eric Dumazet <eric.duma...@gmail.com> wrote:
> On 02/13/2019 12:37 AM, Stefano Brivio wrote: > > On Tue, 12 Feb 2019 16:42:04 -0800 > > Eric Dumazet <eric.duma...@gmail.com> wrote: > > > >> I do not get it. > >> > >> "ss -emoi " uses almost 1KB per socket. > >> > >> 10,000,000 sockets -> we need about 10GB of memory ??? > >> > >> This is a serious regression. > > > > I guess this is rather subjective: the worst case I considered back then > > was the output of 'ss -tei0' (less than 500 bytes) for one million > > sockets, which gives 500M of memory, which should in turn be fine on a > > machine handling one million sockets. > > > > Now, if 'ss -emoi' on 10 million sockets is an actual use case (out of > > curiosity: how are you going to process that output? Would JSON help?), > > I see two easy options to solve this: > > > ss -temoi | parser (written in shell or awk or whatever...) > > This is a use case, I just got bitten because using ss command > actually OOM my container, while trying to debug a busy GFE. > > The host itself can have 10,000,000 TCP sockets, but usually sysadmin shells > run in a container with no more than 500 MB available. > > Otherwise, it would be too easy for a buggy program to OOM the whole machine > and have angry customers. Ouch, I see. > > > > 1. flush the output every time we reach a given buffer size (1M > > perhaps). This might make the resulting blocks slightly unaligned, > > with occasional loss of readability on lines occurring every 1k to > > 10k sockets approximately, even though after 1k sockets column sizes > > won't change much (it looks anyway better than the original), and I > > don't expect anybody to actually scroll that output > > > > 2. add a switch for unbuffered output, but then you need to remember to > > pass it manually, and the whole output would be as bad as the > > original in case you need the switch. > > > > I'd rather go with 1., it's easy to implement (we already have partial > > flushing with '--events') and it looks like a good compromise on > > usability. Thoughts? > > > > 1 seems fine, but a switch for 'please do not try to format' would be fine. Let me try with 1. first then -- we already have a huge number of switches. > I wonder why we try to 'format' when stdout is a pipe or a regular file . As stupid as it might sound, I just didn't think of fixing that :) What would you suggest in that case, single whitespaces? Tabs? -- Stefano
