Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On 20/12/16 13:15, Peter Zijlstra wrote: > On Tue, Dec 20, 2016 at 02:04:34PM +0100, Dietmar Eggemann wrote: >> Hi Samuel, >> >> On 12/20/2016 12:45 AM, Samuel Thibault wrote: >>> Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On 20/12/16 13:15, Peter Zijlstra wrote: > On Tue, Dec 20, 2016 at 02:04:34PM +0100, Dietmar Eggemann wrote: >> Hi Samuel, >> >> On 12/20/2016 12:45 AM, Samuel Thibault wrote: >>> Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Dietmar Eggemann, on Tue 20 Dec 2016 14:04:34 +0100, wrote: > On 12/20/2016 12:45 AM, Samuel Thibault wrote: > >Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: > >>On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault > >> wrote: > >>>Paul Turner, on Mon 19 Dec 2016

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Dietmar Eggemann, on Tue 20 Dec 2016 14:04:34 +0100, wrote: > On 12/20/2016 12:45 AM, Samuel Thibault wrote: > >Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: > >>On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault > >> wrote: > >>>Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: > >

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On Tue, Dec 20, 2016 at 02:04:34PM +0100, Dietmar Eggemann wrote: > Hi Samuel, > > On 12/20/2016 12:45 AM, Samuel Thibault wrote: > >Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: > >>On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault > >> wrote: > >>>Paul

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On Tue, Dec 20, 2016 at 02:04:34PM +0100, Dietmar Eggemann wrote: > Hi Samuel, > > On 12/20/2016 12:45 AM, Samuel Thibault wrote: > >Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: > >>On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault > >> wrote: > >>>Paul Turner, on Mon 19 Dec 2016

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Hi Samuel, On 12/20/2016 12:45 AM, Samuel Thibault wrote: Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault wrote: Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: [...] The MIN_SHARES you are

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Hi Samuel, On 12/20/2016 12:45 AM, Samuel Thibault wrote: Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault wrote: Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: [...] The MIN_SHARES you are seeing here is overloaded. In the

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: > On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault > wrote: > > Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: > >> >> > - if (shares < MIN_SHARES) > >> >> > - shares = MIN_SHARES; >

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Paul Turner, on Mon 19 Dec 2016 15:32:15 -0800, wrote: > On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault > wrote: > > Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: > >> >> > - if (shares < MIN_SHARES) > >> >> > - shares = MIN_SHARES; > >> > ... > >> >> >

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault wrote: > Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: >> >> > - if (shares < MIN_SHARES) >> >> > - shares = MIN_SHARES; >> > ... >> >> > return shares; >> > >> > This will only

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On Mon, Dec 19, 2016 at 3:29 PM, Samuel Thibault wrote: > Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: >> >> > - if (shares < MIN_SHARES) >> >> > - shares = MIN_SHARES; >> > ... >> >> > return shares; >> > >> > This will only make sure that the returned

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: > >> > - if (shares < MIN_SHARES) > >> > - shares = MIN_SHARES; > > ... > >> > return shares; > > > > This will only make sure that the returned shares is 2, not 2048. > > This is intentional. The MIN_SHARES you

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Paul Turner, on Mon 19 Dec 2016 15:26:19 -0800, wrote: > >> > - if (shares < MIN_SHARES) > >> > - shares = MIN_SHARES; > > ... > >> > return shares; > > > > This will only make sure that the returned shares is 2, not 2048. > > This is intentional. The MIN_SHARES you

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On Mon, Dec 19, 2016 at 3:07 PM, Samuel Thibault wrote: > Paul Turner, on Mon 19 Dec 2016 14:44:38 -0800, wrote: >> On Mon, Dec 19, 2016 at 2:40 PM, Samuel Thibault >> wrote: >> > 2159197d6677 ("sched/core: Enable increased load

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On Mon, Dec 19, 2016 at 3:07 PM, Samuel Thibault wrote: > Paul Turner, on Mon 19 Dec 2016 14:44:38 -0800, wrote: >> On Mon, Dec 19, 2016 at 2:40 PM, Samuel Thibault >> wrote: >> > 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit >> > kernels") >> > >> > exposed yet another

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Paul Turner, on Mon 19 Dec 2016 14:44:38 -0800, wrote: > On Mon, Dec 19, 2016 at 2:40 PM, Samuel Thibault > wrote: > > 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit > > kernels") > > > > exposed yet another miscalculation in calc_cfs_shares:

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

Paul Turner, on Mon 19 Dec 2016 14:44:38 -0800, wrote: > On Mon, Dec 19, 2016 at 2:40 PM, Samuel Thibault > wrote: > > 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit > > kernels") > > > > exposed yet another miscalculation in calc_cfs_shares: MIN_SHARES is > > unscaled, >

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On Mon, Dec 19, 2016 at 2:40 PM, Samuel Thibault wrote: > 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit > kernels") > > exposed yet another miscalculation in calc_cfs_shares: MIN_SHARES is unscaled, > and must thus be scaled before being

Re: [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

On Mon, Dec 19, 2016 at 2:40 PM, Samuel Thibault wrote: > 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit > kernels") > > exposed yet another miscalculation in calc_cfs_shares: MIN_SHARES is unscaled, > and must thus be scaled before being manipulated against "shares"

[PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels") exposed yet another miscalculation in calc_cfs_shares: MIN_SHARES is unscaled, and must thus be scaled before being manipulated against "shares" amounts. Signed-off-by: Samuel Thibault

[PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics

2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels") exposed yet another miscalculation in calc_cfs_shares: MIN_SHARES is unscaled, and must thus be scaled before being manipulated against "shares" amounts. Signed-off-by: Samuel Thibault Cc: Peter Zijlstra Cc: Thomas